Frequently Asked Questions

No longer possible.

With the recent changes on Microsoft servers, the IMAP protocol for Outlook/Hotmail/Live/MSN/etc. accounts can be unusable for some external applications at this time.

Please set up your account as Exchange.

• Download the attached registry file in this article.
• Run it while eM Client is still closed and confirm the changes it will make.

If you'd like to add the needed registry key manually instead of using our provided file:

• Run Regedit
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Add the DWORD item AllowExchangeOnlineOAuth and set its value to 0
• Then run eM Client 

To set up the actual account:

• Go to Menu > Accounts.
• Click the '+Add account' button.
• In the New Account window select Mail > Exchange.
• Use your Microsoft mail address for both the Email and Username fields. 
• Finish the rest of the setup
• Delete or disable your previous IMAP setup.

NOTES: Detection of Exchange setup might take longer than usual, but unless an error pops up, let the configuration finish.

If you use 2-factor verification, you might need to create and use an App password for eM Client.

Exchange Web Services protocol will synchronize your Mail, Contacts, and Calendar - you do not need to worry about any data loss because this information is saved on your mail server.

If you upgraded from eM Client 6, your data hasn't been actually lost - you just accidentally skipped database migration.

Since eM Client 7, we have created a completely new database structure for more efficient data storage, so the data cannot be just loaded from the old database as was possible in the past.

To migrate your data manually please use the Menu > File > Import.. > Import from eM Client 6 option.

If you upgraded from eM Client 7, the database should be upgraded automatically, since eM Client 8 keeps to the same model and can upgrade these files automatically, no migration is needed.

In this case, the issue might be with your storage location - make sure that the storage folder in Menu > Settings > General > Storage is pointing to the correct location where your eM Client 7 database was stored.

Please try the following steps to get rid of any 'ghost' messages:

• Turn off Conversations (Menu > View > Conversations > Disable Conversations)
• Close eM Client
• Open RUN function from the Start menu
• Run the command "C:\Program Files (x86)\eM Client\MailClient.exe" /dbrepair
• (For MS Store version of eM Client the command is eMClientStore.exe /dbrepair )
• Wait until the database check is completed
• Turn eM Client on
• You should then be able to set any Conversations setting you prefer.

For IMAP and Exchange accounts only:

• If that doesn't help, please right-click on the folder that the messages are in, select Properties > Repair and click the Repair button.
• This will prompt the resynchronization of this folder from the server and should reset its data.
• You can also try removing your account from eM Client and then adding it again in Menu > Accounts.

Please note that all locally stored data will be lost, but if you have your data on the server, that shouldn't be of concern.

You can make a backup just to be on the safe side through Menu > Backup.

1. If you’re getting an error message, please enclose a screenshot of the error.

2. Send us the whole content of the ‘Log’ tab.
If an error appears, you can access the log by clicking on the third tab in the same window as the Error. If no error appears, go to Menu > Operations, click the 'Copy log' button and paste the log (Ctrl+V) in a message to us.

3. Send us the full number of the version that you’re using (you can find this information in Menu > Help > About).

4. Try to remember what changes you’ve made in eM Client or in your system before the problem started and describe them to us.

Submit the report via one of our Support options or send it to [email protected] (if you're still using the Trial version) and we’ll do our best to resolve the issue as soon as possible.

If you get an error indicating that your database is corrupted, the fastest way of getting eM Client running again is to restore your data from a backup.

This option will be available either from the window informing you about the results of the database check or from eM Client’s interface in Menu > File > Restore.

If you can’t access eM Client to restore the data, please follow the information below on starting with a new database to open the program.

To start with a new database, turn eM Client off and rename the "eM Client" database folder (default location is in hidden folders AppData\Roaming, the whole path is C:\Users\%username%\AppData\Roaming\eM Client) to e.g. ‘eM Client old database’.

Please note that eM Client must stay turned off during this process. Check for eM Client or mailclient.exe in the Task Manager and if you see a process with either of these names, end it before you proceed.

If you do not have a backup but still have all your data saved on the server, you will have to start with a new database, re-create your accounts from scratch and wait until the data is synchronized again.

The special folders in Favorite folders collect messages from all accounts. If there are copies of the same message it can mean the message is copied into more folders or among more accounts.

Common causes for this include:

• Duplicate setup - make sure each of your accounts is set up only once in Menu > Accounts, or all messages will appear twice in Favorite folders
• Rules - do you have any rules that are meant to copy incoming messages? Check the Menu > Rules to make sure that there isn't a rule creating unwanted copies.
• Forwarding - do you perhaps have a server-side forwarding set for one of your accounts? If you don't want messages from one account to always be forwarded to another, check your server rules, for example through webmail

Note: In eM Client 6 this problem also sometimes happened with Gmail accounts, which keeps a copy of each message in All Mail folder and also created copies in Important and Starred labels.
Since eM Client creates a separate folder for each label, emails that have multiple labels attached to them will have multiple copies saved. The only workaround for that issue is to disable the showing of redundant labels like "Starred" and "Important" in IMAP. You can find this option by opening a web browser and logging in to Gmail. Click on Settings, and then go to the tab at the top called "Labels".

Since eM Client 7.0 we have adapted Gmail's internal structure. All messages have just one copy in the All Mail folder and other folders are just assigned labels.

It’s important to realize how eM Client works with IMAP: it only downloads message headers by default to make synchronization more efficient and to save space on your device.
Messages themselves are fully downloaded once you click on them to show their content in eM Client. Thus, eM Client cannot search in the bodies of all your messages by default.

If you’d like to search inside the messages, you can download your messages for offline use.
This setting is available in Menu > Accounts - the account that you’d like to download the emails for - IMAP tab - Offline - "Download messages for offline use".
You can also include images and attachments (if you want to search inside text attachments).

POP and EWS accounts download full messages automatically.

This is a known issue with selected Yahoo servers because Yahoo does not officially support subfolders at all.

That is why the subfolders created in eM Client can disappear after synchronizing with the Yahoo server. The server will clear them out.

We suggest only using top-level folders in Yahoo to make sure no messages get lost.

We have enhanced the IMAP certificate checks so this is an expected result when your certificate name does not match the hostname. Please either use the correct certificate or match the server address found in your account settings (Menu > Accounts > the relevant account - IMAP tab - Host) with the one in the current certificate details.

If you are redirected on the server and the names can’t match, you can also choose the possibility to connect with the current settings and remember this choice.

When setting up a POP3 account using the automatic or manual account setup, you can choose between creating a separate folder tree in the left pane for your POP3 account, or you can have your items synchronized with the default local folders tree.

Both options will store your emails locally as POP3 accounts do not keep your items synchronized with the server and are only used to download new data. Having the account in the left pane will allow you to move the account in the list of your accounts, having it listed under local folders will, on the other hand, reduce the number of listed accounts.

This choice cannot be changed after the setup, you will need to set up the account anew. Be careful not to accidentally remove your messages when doing so, you can always create both setups at once, copy your messages and then remove the unwanted setup.

Microsoft has unfortunately decided to stop supporting Skype for 3rd party applications so this feature had to be removed from eM Client. eM Client does not provide VoIP functionality, but clicking on the phone number in the Contact section of the Sidebar (on the right side of the main eM Client window) results in the standard call-to action, which should detect your default VoIP app and dial the number.

Unfortunately, Facebook has decided to quit Facebook Chat support for third-party applications as of April 30th, 2015. Therefore, this functionality has been removed from eM Client as well.

For IMAP accounts eM Client by default only downloads the headers of incoming messages and the body content is downloaded once you open the message's details.

While the startup synchronization is being processed by your server, it's possible the request for downloading body content may have timed out and can be run again once the folder sync is finished.

To avoid this, try to enable the "Download messages for offline use" on your account or one of your folders – for example, your Inbox.

To do so, navigate to your account settings, IMAP, and check the option to download messages for offline use, or right-click your folder, navigate to its properties and enable the option for selected folders only.

This warning is a general connection error, and it can be caused by minor connectivity issues between the application and your mail server. It can occur when the server is not responding or if the number of requests is higher than usual and the server is unable to respond while the request is valid.

Don't worry though – eM Client should be able to automatically reconnect if the connection error is thrown unless there's a real problem on the server.

You can find more details on what causes this connection issue in the third tab called Log in Menu > Operations. If you need help analyzing the problem, get in touch with our support.

This window is a normal step of Gmail accounts set up, as can be seen in our step-by-step Gmail/G Suite setup on our website.

It's part of Google's authentication called oAuth, where instead of giving the external application (eM Client) your password, you just give access from your Google account settings.

So, log in with your Gmail account and allow access for eM Client by clicking on "Accept" on the second browser page right after you log in to the browser.

eM Client will be granted an authentication token that you can revoke at any time using your online Google accounts settings.

Read more in our blog: OAuth authentication with Gmail

If you try to upload or change an event, task or contact but an error message pops up with the reason described in the message (e.g. invalid value, missing or empty field) it means that there is an invalid item that you're trying to synchronize with the server.

Try to delete the local changes to stop the synchronization – if this cannot be done manually or the error message cannot be closed (or keeps reappearing) it might be best to clear the local cache memory in eM Client for this account and download the correct data from the server.

Simply right-click the affected folder (calendar, contacts folder, etc.), select Properties and open the Repair tab. Click the ‘Repair’ button and wait for the resync to finish.

This issue started happening in eM Client 7.0 when we changed the way we work with Gmail. Since we started supporting Gmail labels and folder structure, all labels are synchronized.
And one thing that was not visible before (and might not be visible in other clients) is that Gmail assigns the 'Important' label to all messages synchronized through IMAP.

In eM Client 8.1 we added a workaround in the Menu > Accounts section under the IMAP tab.

Under the Tag section you will find the Show Important tags option and you can select to either show it based on Gmail's settings, Always show it or to Never show it. 

LEGACY OPTIONS

In older versions, you need to go to your Gmail settings in your web browser and create a filter that will remove the Important label automatically from each message.

To achieve this, go to Gmail webmail, open Settings > Filters and Blocked addresses. Create a new filter where all messages received by your email address will never be marked as Important.

Screenshots of such filter setting can be found below:

Note: You can either apply the filter directly to all previous conversations or open the Important folder/label and manually select all messages to remove the Important label

Blacklist is managed in menu > Settings > Mail > Blacklist and whitelist. The ‘Manage Blacklist’ button will open a window where you can add or remove any email addresses or domains.

Local blacklist is available to everyone. From eM Client 10.1, we also offer support for server-side Blacklist as well as Whitelist for IceWarp and SmarterMail accounts.

You can read about the Blacklist and Whitelist feature in more detail in our blog post here: eM Client Blacklist & Whitelist

eM Client 9 and older:

You can view and manage the Blacklist rule in menu > Rules on Windows or in Tools > Rules on macOS. Just select the Blacklist and click the 'Edit' button.

A new window with all the domains and addresses in your blacklist will pop up and you can add new items or remove any of the email addresses and domains already in it.

Microsoft has officially ended support for Windows XP on April 8, 2014.
Unfortunately, this means that the security protocols from the last service update are no longer up to the current standard.

So when you try to activate the license after the eM Client trial, you will encounter an error message instead, because the request sent from Windows XP, unfortunately, doesn't arrive at our licensing system.

A problem has occurred when contacting the licensing server:

The underlying connection was closed:  an unexpected error occurred on a send.

We have created a compatibility version for XP which allows the connection, but please be aware that this version will not be updated in the future.
Please send us a message to [email protected] if you are interested in this version.

If the program somehow switched to a language you do not understand, do not worry!

The buttons are located in the same place for all localizations, so follow these screenshots to find your way to the language settings:

1. On Windows: Open menu > Settings in the main window. Menu is in the top left corner of the program, Settings is a 9th item on the list in the drop-down menu. On macOS: Open eM Client > Settings, the 9th item on the list in the drop-down menu.

2. This will open the Settings window. Here you want to open the General > Language section. General is the very top section while Language should be the 3rd one in the list below. 

3. Then just select your preferred language and press Ok.     

The Operations log can be very useful for troubleshooting, as it contains information about the Operations that were done during this run of the application. If there is an error message the Operations log might contain more detailed information about the error itself.

If an error message already popped up, the Log can be found in the third tab of the same Window. Otherwise, you can open this window manually in Menu > Operations. The Log is in the third tab of this window.

Simply click the Copy log button and then paste the text into a text editor (Notepad, MS Word, ...) via the Ctrl+V shortcut.

You can then search for your error message there in case the error details made the reason self-explanatory or you can send this log to the support so we can analyze it and provide advice.

Support options are described on our website in Support overview section. 

LEGACY OPTION

In older versions the Copy log button is not available, so you will need to copy the log manually.

• Open the Log tab and then click inside, to select a single line
• Press Ctrl+A keyboard shortcut to select all the lines
• Use Ctrl+C to copy the content
• Open a text editor (Notepad, MS Word, ...) and use Ctrl+V to paste the log there and then send it to support.

Unfortunately, Gmail does not forward the information about the label color through IMAP protocol, so eM Client cannot load the exact same colors and assigns random ones instead.

However, if you go to Menu > Tags and create a new tag with the same name as your Label, you will be able to select your own color in eM Client.

This workaround will work for all top-level Folders/Labels, not subfolders.

This is, unfortunately, a common confusion, as there are actually two different settings for changing your font style in eM Client. One is your preferred style for reading messages and the other for writing/composing a message.

1. Menu > Settings > Mail > Read

The Preferred Style setting in this section will be applied to the messages you read, if they use Plain text. Plain text format does not have any set "visual" formatting, so you can apply your own.
This way you can make the font easier to read for you.

The setting will not be applied to HTML messages, which do have set formatting.

2. Menu > Settings > Mail > Compose

The Preferred Style in this section will be used for writing all your messages.

If any of the main left-side sections is missing, whether it's Mail, Calendar, Tasks or Contacts your data is definitely not gone. It just means you accidentally hid the section.

You can make it appear again easily.
Just right-click any of the other items in the same menu (for example Calendar) and a drop-down menu with all options will appear. The missing section will not have a checkmark next to its name.
Click it to check it and make it appear again.

Users of BTinternet email accounts have recently seen a variation of these errors:

[IMAP] Cannot open folder ... ([Clientbug] Select additional arguments found after last expected argument)

[IMAP] Cannot open folder ... (unrecognized extra arguments to SELECT command)

We have analyzed the issue in detail, including IMAP logs provided by some of our users and our developers concluded that it's a server issue that can't be fixed on our side, unfortunately.

It seems that the BT updated the feature on their back-end servers but didn't adapt the proxy servers which report the errors. It seems that BT is continuously changing the settings and that's why sometimes the account reset helps but later on the issue reappears.

Some tweaks to the settings seem to help though, these are solutions provided by our users:

"A bit of research reveals that BT uses two versions of mail - BT email and BT Yahoo email. See here

http://bt.custhelp.com/app/answers/detail/a_id/57483/~/im-not-sure-if-ive-got-bt-mail-or-bt-yahoo!-mail

By logging into the desktop version of BT email you can see which version you have got. It transpires I have BT Yahoo mail. I have set the email up using BT Yahoo settings and it is now working again. Something must have changed on BT's side. So if you get this query again this should be the solution."

Another tip that seems to help is filling in the manual option for credentials under the IMAP tab in Menu > Accounts. Open this section and open the IMAP tab for your BT account. Insert your credentials into "these credentials" fields and save the settings.

Also, if your username is set anywhere as just the user part, make sure to change it to full address - ie. if the full email address is [email protected] make sure the user name is set to "[email protected]", not just "example".

Update: NTLM is now supported in eM Client 8.2 and newer

In case you're trying to set up an Exchange account in eM Client for Mac and you're getting pop-ups with failed authentication, then your mail server most likely requires an NTLM authentication, which is currently not supported in eM Client for Mac.

We are aware of the problem and are collaborating with Microsoft on a solution that will solve this once and for all.

A possible workaround is setting the account up with IMAP protocol manually via eM Client > Add account > Mail > Other or ask your mail server administrator if there are some other authentication methods available for Exchange protocol on your server.

Attention: These solutions can only work with eM Client 8.0 - 8.1, they will not work for legacy versions of eM Client. eM Client 8.2 and newer do not need this solution, as it is included natively.

eM Client supports MFA/oAuth login, but the pop-up window for this authentication method will not be allowed to be used by default on your device.
That is why the login method will not work natively for now, but we have prepared workarounds to help you out:

eM Client for Windows

• Download the attached registry file in this article.
• Run it while eM Client is still closed and confirm the changes it will make.
• Run eM Client and use the automatic setup to set up your accounts with oAuth.

If you'd like to add the needed registry key manually instead of using our provided file:

• Run Regedit
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Add the DWORD item AllowExchangeOnlineOAuth and set its value to 1
• Then run eM Client and use the automatic setup to set up your accounts with oAuth.

eM Client for MacOS

• Open the Terminal
• Execute this command:
• defaults write com.emclient.mail.client AllowExchangeOnlineOAuth -bool TRUE
• Run eM Client and use the automatic setup to set up your accounts with oAuth. 

WARNING: If you use this work-around please make sure to disable the 'Offline Address Book' service during the last step of the setup.It is not compatible with the oAuth setup and could cause additional problems with the setup.

Our databases are not backward compatible for older versions and once you upgrade your database to accommodate the new version, you cannot just simply install an older version over it.

If you have a backup of your database from eM Client 10 or older you can skip any export. If not, you will need to export local data before the downgrade to keep them.

For accounts set up with IMAP or EWS protocol this is not an issue, as setting these accounts anew will synchronize messages and folders back from the server.

For POP accounts and any data in Local folders, export them first via Menu > File > Export and once you downgrade, you can import them back via Menu > File > Import.

The steps to downgrade on Windows are to:

• Export any local data you need to keep (menu > File > Export)
• Uninstall eM Client 11
• Either delete the database or rename it (the default location is in C:\Users\%username%\AppData\Roaming\eM Client)
• Install your preferred older version of eM Client (You can find older versions in our Release history)
• Restore from the backup (Menu > File > Restore) or create your accounts anew and import your local data back in (Menu > Accounts, Menu > File > Import)

The steps to downgrade on macOS are to:

• Export any local data you need to keep (File > Export)
• Uninstall eM Client 11
• Either delete the database or rename it
• Install your preferred older version of eM Client (You can find older versions in our Release history)
• Restore from the backup (File > Restore) or create your accounts anew and import your local data back in (eM Client > Add account, File > Import)

If you want to delete or rename your database, the default location is in /Users/User Name/Library/Application Support/eM Client

If you upgraded by accident and aren't sure if you need to downgrade manually, please see the article on this topic - This version of eM Client is newer than what your current license permits.

Note: These same steps can be used to downgrade from a BETA version to the current eM Client official version - just uninstall the BETA and reinstall current version from the website

If you use Google or Yahoo accounts your accounts might have stopped synchronizing after the upgrade. This is most commonly caused by external apps like Antivirus, Firewalls, VPNs, etc. which are blocking the new version of eM Client for your safety because the program is new and therefore not in any trusted databases of these programs.

We have seen this often happen with Avast, Kaspersky and AVG, though others could cause the same problem.

Adding eM Client to exceptions in these apps and disabling any mail shields should resolve the issue.

We also recommend reporting this to the provider of your security app, so they can update their records and not block eM Client in the future.

Upon upgrading to eM Client 8, all your folders were “hidden” by default under a folder called 'More'. This was to give you a fresh start with your folder management and make the interface more streamlined.

To remove items from the More folder, simply drag them out of it. Once there's nothing in the folder, it will disappear. To add items back, simply right-click an item and select Hide.

Alternatively, you can manage which items are hidden under the More folder or shown on your folder list by right-clicking your email account name in the folder list and selecting Show/hide folders.

Previous versions of eM Client had several important features (such as Settings, Operations and Accounts) which were embedded under Menu > Tools. Therefore, a lot of our documentation and help articles written before the release of eM Client 8 in June 2020 have instructions that follow that pathway. With eM Client 8, we promoted some of these frequently used features to just be under Menu. Additionally, some features (such as Categories and Smart folders) have been renamed.

The release of eM Client 8 has brought enhanced search capabilities, including searching in the text of attachments and on IMAP and Exchange/Office365 servers. Sometimes though, searching through the mail server does not return correct/expected results, so it might be beneficial to turn off server search and search locally within eM Client instead.

To do this click on the down arrow v on the right side of the search bar and deselect Use server search if available. Also, while you’re in this search menu, double check that you’ve selected the correct search parameters, such as searching in All folders and searching for your keyword in the Subject, Sender, Recipients, Body and Attachments fields.

Read more in our blog: Search Like a Pro in eM Client

Most users nowadays have high-speed internet connections and therefore an explicit progress bar for sending messages was no longer necessary in Version 8.

However, if you still want to monitor the progress of your sent emails and updating folders, you can open the Operations window by going to Menu > Operations.

If you want the Operations window progress bar to always be displayed as you send and receive messages, you can turn on this feature under Menu > Settings > General > General > Operations Window and select the box for Show window on send and receive.

When you go to type in a name in the To: section, if there is an X button on the right side in the suggestion list, then it can be deleted from the history of recipients via click on that button.
Otherwise, the unwanted contact must be deleted from your address book or the messages sent to this email address from the Sent folder.

You can also adjust your suggested recipients list by going to Menu > Settings > Mail > Compose > Email Address Suggestion.

Suggestions based on messages in Sent folders and Recipients history based on your use in eM Client can be turned off; suggestions based on your saved Contacts cannot be disabled.

This is a known issue with some Gmail events and system notifications, you can resolve this by unchecking the Use system notifications box in Menu > Settings > General > Notifications.

We believe that the slowness of the new version is likely due to the attachment indexation and folder syncing. You can try leaving eM Client running overnight so it can complete this process.

Alternatively, you can run the eM Client application with a disabled indexer by pressing the Windows key and R key at the same time and entering the following command:

"C:\Program Files (x86)\eM Client\MailClient.exe" --disable-attachment-indexer

(Unfortunately, there's not currently a similar workaround for Mac OS)

We’re also working hard on fixing the speed issue and bringing you better performance with future updates.

Generally, Pro Support is only available to Pro License holders for one year after their purchase, otherwise we direct Free users to our Support Forum.

However, since the new eM Client 8 was recently released, everyone is treated as a Pro user for a month and is contacting the Support Team for a large range of issues. This has greatly increased our number of new support tickets to 100s every day and created a backlog. Some of the issues are bugs that our users have caught and we can pass on the information to our developers to fix and make eM Client better for everyone.

We’re happy to help you and we promise that your ticket has not been forgotten or lost, but your patience is greatly appreciated during this time.

This is likely caused by the system notifications from your operating system. Try going to Menu > Settings > General > Notifications and disabling the "Use system notifications box". Sometimes the system notifications from Windows misbehave and don't work correctly.

When you disable them, the native notifications for the eM Client Application take over and are more reliable.

If you get the following error:

[Google Contacts]Uploading item(s) to folder '[email protected]/Contacts' failed due to the following error: Execution of request failed: https://www.google.com/m8/feeds/contacts/default/full (Invalid request.)

The first thing you should know is that most of the "folders" of Google's mail, contacts, tasks, calendar, etc. are just a complex Tag system that's pretending to be folders.
When objects (messages, events, contact entries etc.) are without a Tag to sort them somewhere, strange things and errors start to happen. Understanding that will help you understand the rest of the explanation and the solution.

It seems that if you click the orange + New > Contact button then it will typically default to the root /Contacts folder, which is what's causing your error. If you're creating a new contact using that method, you must either select a Tag to apply to the folder or select a subfolder.

The way to change the default is to select any of the subfolders before clicking the orange + New > Contact button. Then it will automatically apply a tag to the contact and it won't trigger the error.

To fix the rest of your contacts that have this "No Tag" error, the easiest thing to do would be to go to the Contacts folder and sort all of your contacts by Tag in ascending order. This will cause all your "unsorted" contacts to appear at the top. Drag all of the unsorted contacts into any of your subfolders and this will apply a tag to them and stop the error. It could also be helpful to click the "select" option so that you can easily select multiple entries at once.

After uploading your Public Key to eM Keybook, you might have received a message saying:

Uploaded Public Key not Verified

Public Key John Doe for email address [email protected] was uploaded to eM Keybook, but has not been verified yet. Should eM Client keep monitoring for incoming verification emails?

This occurs when you have not yet checked your email to confirm that you would like to upload your Public PGP Key to eM Client. The message you should be looking for is called "Verification email from eM Keybook" and it will be sent from [email protected].

Furthermore, some email accounts (such as @seznam.cz, @yahoo.com, or @aol.com) have a problem if checking the message through normal means does not trigger the confirmation.

The workaround for this problem is as follows:

1. Right-click on the "Verification email from eM Keybook" message in your list of emails in your inbox and select "Save as" and then save the email as a .eml file.
2. With this .eml file you exported, go to your file explorer in Windows where you've saved it on your computer and open the file with eM Client.
3. When the .eml file is open click Menu > Message > Copy to Folder
4. Choose where you want to save a copy of the message in eM Client.
5. Navigate to where you saved the file within eM Client, and it should be displaying/working correctly and the verification will trigger.

eM Client uses external service for translations, so it has to pay for each translation made through its interface. For this reason, Free license users have limited access to this feature.

There are no limits for paid licenses.

Read more in our blog: On-the-fly Email Translation in eM Client and in the Documentation: Spell-checker and translator

Google unfortunately doesn’t support recurring tasks, the information about recurrence is saved locally in eM Client. If you remove and add your account again this information is lost, because the local data has been cleared and the newly synchronized data from the server does not contain the recurrence information.

Some servers might not support distribution lists and can therefore try to change the list into a regular contact, leaving only the first email address. To prevent this, please save your distribution lists into eM Client’s Local folders. The list will not be synchronized but you will be able to use it from the application’s interface.

Read more in the Documentation: Distribution List

On June 15th, 2021 Google phased out the Google Contacts API, which is a protocol we used for synchronizing Google contacts in older versions of eM Client. If you are still running one of these versions, you will encounter this error:

[Google Contacts] Synchronizing folder '[email protected]/Contacts' failed due to the following error: Execution of request failed:

(Contacts API is being deprecated. Migrate to People API to retain programmatic access to Google Contacts. See https://developers.goog.ecom/people/contacts-api-migration.)

We have switched to the current People API in eM Client 8.2, so if you are running any of the older versions, you need to either install the update (if your license is valid for eM Client 8) or upgrade your license and then install it.

You can of course keep using the older version if you prefer, but you will not be able to synchronize your Google contacts anymore, they will only be stored locally as they are.

To avoid the error pop-up, you can work around this situation by copying the contacts to Local Folders and switch off the Google Contacts service in Accounts settings.

Go Daddy servers are rejecting the version of Chromium in our application, so the secure OAuth login in our native browser window during the account setup could not finish. The error messages that shows up when this happens is:

Your Browser is a bit unusual...
Try disabling ad blockers and other extensions, enabling javascript, or using a different web browser.

We have created a fix version which will use your default web browser instead of our native window for this authentications. Please download this version here: https://www.emclient.com/dist/v8.2.1509/setup.msi

UPDATE 9/30/2021: Microsoft has now fixed their OAUTH and the automatic setup will work again.

On September 24th, 2021 Microsft made some changes on their mail servers, which disabled OAuth login for the IMAP protocol on their accounts. Unfortunately, this affected all outlook.com, hotmail.com, live.com, msn.com and other free Microsoft account domains in our program, since we used this secure login method as default.
You can tell if your account is affected by a red triangle shown next to your account name. This account also cannot receive any new messages.

The workaround at this time is to set up the account anew manually either as Exchange or as Other (IMAP) to avoid usage of the IMAP-XOAUTH2 login.

Note: If you use 2-factor verification, you might need to create and use an App password for eM Client.

Manual IMAP setup (Other):

• Go to Menu > Accounts.
• Click the '+Add account' button.
• In the New Account window select Mail > Other.
• Insert your Microsoft account address
• Select IMAP.
• Insert these settings for Incoming server: imap-mail.outlook.com
• Outgoing server: smtp-mail.outlook.com
• Finish the rest of the setup
• Delete or disable your previous IMAP setup

Exchange setup:

• Download the attached registry file in this article.
• Run it while eM Client is still closed and confirm the changes it will make.

If you'd like to add the needed registry key manually instead of using our provided file:

• Run Regedit
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Add the DWORD item AllowExchangeOnlineOAuth and set its value to 0
• Then run eM Client 

To set up the actual account:

• Go to Menu > Accounts.
• Click the '+Add account' button.
• In the New Account window select Mail > Exchange.
• Use your Microsoft mail address for both the Email and Username fields. 
• Finish the rest of the setup
• Delete or disable your previous IMAP setup. 

One of the largest certificate issuers Let’s Encrypt had their root certificate validity end on 30. 9. 2021. In case your validity has not been renewed, an error might occur with eM Client licensing and other programs as well.

How to check your certificate validity in Windows?

1. Navigate to the Start menu in Windows and type certmgr
2. Open the Certificate Manager app by pressing enter and allow changes
3. In the left window navigate to Third-Party Root Certification Authorities
4. Click on the file Certificates that shows up
5. Go to the right side and find ISRG Root X1 in the ‘Issued to’ column- it is ordered alphabetically
6. Check the expiration date in the third column

Now, in case your certificate has validity to 30.9.2021 it means it is past due. 

Here is how to solve the problem.

1. Download the attached file 'ISRG Root X1.cer' and open it on your PC
2. A window pops up, click on Install Certificate
3. Click Next on the following screen
4. Check the option to Place all certificates in the following store
5. Click Browse and select Trusted Root Certification Authorities and click OK
6. Click on Next and then Finish to import the certificate

How to solve this issue on Mac?

Remove the old ISGR Root X1 certificate from your Keychain and then download the attached file 'ISRG Root X1.cer'

When using an account that is running on an Exchange server provided by Microsoft, you can encounter this error:

Known Microsoft Exchange server error "User is authenticated but not connected" has been encountered on IMAP connection. This issue is temporary and should be automatically resolved by the server. If not, please contact your mail provider.

This error means that the authentication process for your account was succesfull, but for some reason the mail server is not giving eM Client access to the account data, so it cannot synchronize your messages into the app.

This can have a few different causes - sometimes it's a temporary issue that will go away on its own, but lately we had this issue reported with brand new outlook.com accounts that do not have IMAP protocol allowed.

• Sign in to your Outlook account via the webmail (https://outlook.live.com/)
• Go to Settings > Mail > Forwarding and IMAP > Login > enter your credentials again
• Enable Allow devices and applications to use POP and Allow devices and applications to use IMAP
• Save your settings and click the Refresh button.

If you already have IMAP allowed and the issue does not clear on its own, reach out to your admin or provider of the email account so they can fix the issue.

If this is happening with an email account that is set up using an Alias and not the Primary email address, try setting up the account anew using the primary email address to see if that resolves the problem.

This article applies to eM Client 9 and newer.

eM Client 9 introduces contact avatars in the message list, but this can make other details harder to see in a more compact view or on smaller monitors.
You can easily disable the avatar feature or at least resize the avatars to take less space.

Resize Avatars:
Go to Menu > Settings > Mail > Read and scroll down to the Message List settings.
There is an Avatar size: option which you can set to Regular or Small.

Remove Avatars:
Right-click the top of the message list and open Columns configuration.
Select the Avatar from the "Show these columns" list on the right and then click the Remove button, which will move it to the list on the left, "Available columns".

If you use Windows system notifications for eM Client and eM Client is already running, you can encounter this error when trying to perform an action directly from the pop-up:

Communication with the previous instance failed. The other instance has to be ended in order to start the application.

This happens if you run eM Client in administrator mode, which is not compatible with Windows notifications. To avoid this issue, make sure to run eM Client as a regular user instead of 'as admin'.

eM Client 9 introduces synchronized signatures, but Microsoft has released an update to some of their servers which unfortunately locks this feature for Exchange Web Services protocol. If you do not see the 'Synced from EWS' signatures for your Outlooks/Exchange accounts please try this workaround:

• In the Outlook Web Application go to Settings > View all Outlook settings > Mail > Compose and reply.

• After that delete all signatures using the Delete button. 

• Then, in section Select default signatures change values For New Messages and For Replies/Forwards to No Signature.

After deleting all signatures Outlook should create the new signature with the name Outlook Web Signature, which will represent your synchronized signature. This signature should synchronize to your eM Client and can be edited.

Note: in case the Outlook Web Signature was not created, please contact Microsoft support with a request to block Roaming signatures.

Some users with the latest eM Client 9 for macOS might have encountered an issue where their messages never finish loading, even though clicking REPLY shows that the message text is available. We have tracked this issue to App-specific region settings, so if you have encountered this issue, please follow these steps:

1. Go to System preferences on your mac device
2. Open Languages and Region
3. Click on the Apps section
4. If there is any app-specific setting for eM Client, remove it from the list (especially if the region is set to Sweden or Norway).
5. Save this change and reload eM Client - your messages should show up correctly now.

Alternative, if there was no app-specific setting

1. Add eM Client here and set English as a language.

In June 2022 Google discontinued their support for less secure login methods for their email accounts. The solution to this is to set up your account anew using the secure OAuth method.
Please read more here: Google ‘less secure apps’ access and what it means for eM Client

eM Client will always try to use the newest TLS protocol available, which of course includes current TLS 1.2 and TLS 1.3 (on macOS, eM Client currently only supports TLS 1.2).

If you've received any of the following emails from your provider:

We are contacting you because one or more of your devices or programs uses the TLS 1.0 and/or TLS 1.1 encryption protocols to connect to our email servers, or is using an unencrypted connection.

We will no longer support TLS v1.0

Then you shouldn't have to worry with eM Client, as it can and will use a more secure connection when available.

If you are using Windows 7 or older system though you might need to make sure that your device supports TLS 1.2, but it can be manually enabled on Windows 7 if needed. Here's a tutorial you can follow.

TLS 1.3 is the fourth version of the commonly used protocol for secure communication on the internet. Unfortunately, not all apps and systems can work with it correctly now, such is the case with Windows 10.

You can view which Windows versions can work with TLS 1.3 on this Microsoft page: TLS protocol version support

Gmail OAuth login on Windows 10
When TLS 1.3 is enabled, this can cause issues with the Google accounts OAuth - the authentication window will show up, but the setup can never be finished, the OAuth window will keep reloading and the eM Client app will not be able to connect to the Gmail server to synchronize your data.
The solution is to run the DisableTLS1.3.reg file attached to this article, start eM Client, and try the Gmail account setup again.

A similar issue can affect Kerio accounts when using Windows 10 as well. The solution is also to disable TLS 1.3 until Microsoft provides the required update to Windows 10.

This solution can also work if you encounter this error when sending or receiving an email:

"Cannot determine the frame size or a corrupted frame was received."

Update 3/2/2023: We have created an alternate workaround which uses AirSync instead of SMTP for sending emails, read more here. 
The new workaround is for eM Client 9.2, so if you use an older version of eM Client and do not wish to upgrade, please feel free to still use the workaround on this page.

In the past few days, users of @outlook.com, @hotmail.com and other free Microsoft email accounts might have encountered an issue when sending emails. 

[SMTP] MailClient.Accounts.AuthenticationAbortedException: Authentication aborted.

This issue is caused by a new problem on Microsoft's modern OAuth login method, settings up the account with an older version of the OAuth authentication in the meantime will work.

For the workaround, follow these steps:

Windows

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Download and run the registry file in this article - useoldoutlookcomflow.reg
  (this file can be downloaded at the bottom of this article, in the Attachments section)
• Open eM Client and log in using the OAuth window that pops up.

macOS

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Open Terminal and run this command: defaults write com.emclient.mail.client UseOldOutlookComFlow -bool TRUE
• Open eM Client and log in using the OAuth window that pops up.

Once Microsoft fixes this issue, you can either keep the older OAuth or remove the workaround with these steps, which are just the reverse of the previous ones:

Windows

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Download and run the other registry file in this article- removeoldoutlookcomflow.reg
• Open eM Client and log in using the OAuth window that pops up.

macOS

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Open Terminal and run this command: defaults delete com.emclient.mail.client UseOldOutlookComFlow
• Open eM Client and log in using the OAuth window that pops up.

eM Client can work with any email account that allows connection to the mail server via POP, IMAP or Exchange (EWS) mail protocol.

Unfortunately, it seems BTconnect.com is making changes to their mail servers and ending support for all external mail apps, except for Outlook mobile apps.

Please read more details in their article: The security of btconnect.com email is being improved

Email provider GMX allows its users to enable more secure authentication for their accounts, the two-factor authentication - https://www.gmx.com/security/2fa

When you enable this additional security layer, you need an app password for other apps to login into your GMX account for you.
Most email service providers will use the same app password for one app, but GMX needs this password per each protocol/service you plan to use in a 3rd party application.

That means that for eM Client you will need three app passwords total - one to receive email via IMAP service, one to send via SMTP, and one to synchronize your contacts and calendars via CalDAV/CardDAV service.
Trying to use the same password on the whole account will result in rejected logins and might resolve in issues connecting to GMX Mail or GMX Calendar depending on where you use the app password.

If you experience problems with eM Client not behaving as default mail client for opening mail files, using Mailto links from web, etc. there might be a specific default setting missing in your system.
The best way to resolve it is to go to your System settings > Apps and then 'Set defaults by app' (Windows 10) or 'Default apps' (Windows 11).

From the list of installed apps select eM Client and then assign all available file and link types to make eM Client function fully as a default app for all email and calendar functions.

If you experience issues using the Send to > Mail recipient function in Windows, the attached registry file can help - simply download it and run it.

Some users experience issues with their Exchange accounts on our mobile app, even though the same account connects correctly on desktop.

This is caused by incorrect NTLM implementation in the .NET platform, which our and many other applications use. This issue is usually triggered on Exchange accounts if you have "Extended protection" enabled on your server and it affects only mobile apps, not the desktop program.

Our developers have created a fix for .NET in its current version .NET 8 and .NET 9, and it should hopefully be merged soon.

https://github.com/dotnet/runtime/pull/102565
https://github.com/dotnet/runtime/pull/95898

Unfortunately, until that happens, we cannot provide any alternative solution - only wait for the fix to be merged into the .NET platform.

If eM Client is missing from your system "Share" menu, it is most likely missing from the location in System Settings/Privacy & Security/Extensions/Sharing

Please open the Terminal and run this command to add back any missing apps:
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -seed

Recently this error started popping up for some Gmail accounts:

[Google Contacts] Synchronizing folder 'Your Google Account/Other Contacts' failed due to the following error: Parameter validation failed for "resourceName" : The value did not match the regular expression ^people/[^/]+$

This error means there has been a problem getting some contacts synchronized from the Google server, specifically in the 'Other Contacts' folder.
This folder works similarly to eM Client's Recipients history - it's Google's folder for saving email addresses you previously sent messages to, so these are usually not contacts created by you, but automatically by the server. Your contacts are in the main Contacts or My Contacts folder. 

Deleting the contacts from 'Other Contacts' and then repairing the folder in eM Client should resolve the issue.

Other Contacts cannot be deleted from external apps though, so you need to go to this page in your browser: https://contacts.google.com/other
Make sure you are logged in into the correct Google account and then delete the items in this folder.
Back in eM Client, open the Contacts section.
Right-click the Other Contacts folder and open Properties
Open the Repair tab and click Repair.

This will re-synchronize the folder and without the invalid contact, the error should not pop up again.

The Received header is not defined by eM Client, but the SMTP server that processes the message.

We send the EHLO command to the SMTP server as defined in RFC 5321.
Your mail server adds the full address-literal into the Received header, which is recommended by the specification.

User-Agent is also standard information given to the server, to identify the source of the email, though other apps can use different non-standard headers for the same reasons, such as X-Mailer (X-Mailer: iPad Mail (18C66) , X-Mailer: Microsoft Outlook 16.0,...).

So these details cannot be removed from your outgoing messages.

In December 2024, some Google accounts stopped showing the Birthday calendar after Google changed the way it handles birthday events. As a result, the eM Client app currently cannot show it.

Unfortunately, this means we'll also need to rework how this functions in eM Client. The possibility to display the Birthday calendar is set to be reintroduced in eM Client 11.

If you set a custom location for your database and the location is not available (for example external drive that is disconnected), you might have trouble running eM Client.
To delete the custom storage location setting open the Terminal and run this command:
defaults delete com.emclient.mail.client DBLocation

Both Gmail and free Microsoft accounts (outlook.com, hotmail, msn, live, and other free domains provided by MS) allow calendar sharing from their web interfaces, but do not allow the sharing settings to be configured from third-party apps such as eM Client.

So to share these folders, you need to access the web interface and share the calendar there - but eM Client will be able to synchronize any calendars shared with you, so you can still view all the shared calendars from inside the program!

If you encounter this error with Word files specifically, the issue might be the Privacy settings in your Microsoft Office apps.

Disable all the "Connected Experiences" in the Privacy Settings of Word (or another Office program this applies to), and you will be able to attach open Word files again. 

eM Client does not use AIA (Authority Information Access) to fetch intermediate or root certificates on demand, and this is intentional for security reasons.

On Windows, trusted certificate authorities (CAs) are managed through the system certificate store. Outlook and some other applications can trigger Windows to fetch missing certificates from trusted CAs when needed. eM Client, however, only uses certificates already present in the Windows store. If an intermediate certificate is missing, it does not try to download it via AIA or force Windows to update its trusted root list (which is normally updated periodically through Windows Update).

This behavior is designed to prevent a type of privacy attack: a malicious sender could include a URL in the AIA field of their certificate pointing to their own server. If your mail client automatically contacts that URL to retrieve a certificate, the sender would immediately know you opened their email.

To avoid issues, make sure to import certificates with their complete chain (including intermediate certificates) into the Windows certificate store in advance.

On macOS and iOS, some eM Client users experienced SMIME certificates error “unknown revocation status.” This also affected some HTTP services, such as the automatic translation.

This is caused by the fact that Apple’s system does not always properly handle certificate revocation checks after Let’s Encrypt deprecated Online Certificate Status Protocol (OSCP) method in favor of Certificate Revocation Lists (CRL). We suspect that Apple does not take CRL into account at this time and since OCSP is no longer available, the status is left "unknown."

eM Client offers a setting, IgnoreUnknownRevocationStatus, to control this behavior now, which has 3 options:

The default behavior since eM Client 10.3.2298 will now ignore this specific error, but you can use these commands to change it:

To explicitly allow SMIME certificates to work, run this command in the terminal:
defaults write com.emclient.mail IgnoreUnknownRevocationStatus -int 1

To Enforce strict validation (this might also block other HTTP services, including eM Client's translation, QR Import, EWS Servers and more):
defaults write com.emclient.mail IgnoreUnknownRevocationStatus -int 0

To return to default behavior:
defaults delete com.emclient.mail IgnoreUnknownRevocationStatus

• Kerberos based SSO – since it doesn’t rely on a web-based prompt.
• System-wide proxy without authentication – since no interactive login is needed.

In some cases, accepted invitations from your Gmail account may appear in eM Client but not in your Google Calendar. One common cause is the custom Google setting for automatically adding events from invitations.

Go to your web browser and open your Google Calendar settings. Scroll down to Event settings > Guest permissions and change it to Add invitations to my calendar "From everyone."

If any other setting is used, Google rejects the events added from eM Client, but does not show any errors or warnings. During synchronization, it seems that the server confirms that all is synchronized correctly, so unfortunately, there is little we can do on our end to avoid this issue.

However, other factors can also cause accepted events not to sync, so if adjusting this setting doesn’t resolve your issue, please contact our support team for further assistance.

To speed up email address suggestions when composing an email, go to menu > Settings > Mail > Compose and disable “Use all recipients from Sent folders for suggestions” under Email Address Suggestion.

Depending on your email history, this option can cause a significant delay since the app needs to load recipients from Sent folders across all your added accounts each time you're composing an email.

Disabling it should resolve the issue, but if you still experience slow address suggestions, you can also try using the Clear recipient history button or deleting specific irrelevant addresses via the Show recipients button. If you only want to use your Contacts for the autocomplete, disable “Store composed mail recipients for suggestion”.
Read more on this feature on our blog.

If you need to show our support team what’s on your screen, taking a screenshot is the easiest way.

Screenshots on Windows 7/10/11:

To take a screenshot of your entire screen:

• Press Windows (⊞) + Print Screen (PrtScn) on your keyboard.
• To send by email:
  • Click in the body of the message.
  • Press Ctrl + V to paste the screenshot.
• To send through the support center:
  • Open the program Paint (press Windows (⊞), type “Paint,” and press Enter).
  • Press Ctrl + V to paste your screenshot into Paint.
  • Press Ctrl + S to save the file somewhere you can find it, like your Desktop.
  • Click Add file under your support ticket and select the screenshot you saved.

To take a screenshot of a single window:

• Click the window you want to capture to make sure it is active.
• Press Alt + Print Screen (PrtScn) on your keyboard.
• To send by email:
  • Click in the body of the message.
  • Press Ctrl + V to paste the screenshot.
• To send through the support center:
  • Open the program Paint (press Windows (⊞), type “Paint,” and press Enter).
  • Press Ctrl + V to paste your screenshot into Paint.
  • Press Ctrl + S to save the file somewhere you can find it, like your Desktop.
  • Click Add file under your support ticket and select the screenshot you saved.

Screenshots on macOS:

To take a screenshot:

• Press Command (⌘) + Shift + 5 on your keyboard.
• A small menu will appear with options. Select one:
  • Capture Entire Screen (screen icon)
  • Capture Selected Window (window icon)
• Click Capture. The screenshot will be saved automatically on your Desktop.
• To send by email: Drag the screenshot from your Desktop into the message.
• To send through the support center:
  • Click Add file under your support ticket and select the screenshot you saved.

If you need to show our support team what’s happening on your screen, a screen recording can be more helpful than a screenshot.

Screen recordings on Windows:

Windows 11 (Snipping Tool)

• Press Windows (⊞) + Shift + R on our keyboard.
• Click and hold your mouse, then drag over the area you want to record.
• Click Start. Three seconds later, it will start recording.
• To stop recording, click Stop.
• A window with your recording will open. Press Ctrl + S to save the file somewhere you can find it, like your Desktop.
• To send by email: Drag the saved file into your email message.
• To send through the support center: Click Add file under your support ticket and select the screenshot you saved.

Windows 10 (Xbox Game Bar)

• Press Windows (⊞) + G on our keyboard.
• If prompted, click Yes, this is a game.
• Press Windows (⊞) + Alt + R to start recording.
• To stop recording, press Windows (⊞) + Alt + R again. The recording will be automatically saved in Videos\Captures.
• To send by email: Drag the saved file into your email message.
• To send through the support center: Click Add file under your support ticket and select the screenshot you saved.

Screen recordings on macOS:

• Press Command (⌘) + Shift + 5 on your keyboard.
• Choose Record Entire Screen (screen icon with a dot).
• Click Record.
• To stop recording, press Command (⌘) + Ctrl + Esc. The recording will be automatically saved on your Desktop.
• To send by email: Drag the saved file into your email message.
• To send through the support center: Click Add file under your support ticket and select the screenshot you saved.

Users with a Microsoft personal account may encounter the following error when trying to create a Teams online meeting in eM Client: “Default calendar is not known”.

In the Online Meeting logs this typically appears as:

• "AuthenticationError – Error authenticating with resource"
• "allowedOnlineMeetingProviders":["unknown"]
• "defaultOnlineMeetingProvider":"unknown"

This issue started after Microsoft retired Skype in May 2025 and moved users to Teams Free. Personal Skype users could sign in and keep their chats and contacts, and Teams initially worked in eM Client.

As the migration progresses, MS personal account users now report being unable to create new online meetings and see the error above.

This is caused by how Microsoft permits online meeting creation:

• eM Client (a third‑party app) must use the Microsoft Graph API to create online meetings.
• Microsoft’s Graph API restricts Teams meeting creation to Microsoft 365 work or school (Azure AD) accounts with Teams enabled and licensed.
• Personal Microsoft accounts are not supported for this API, so the request is blocked and eM Client shows “unknown” as the provider. This is why Teams works in Outlook or the Teams app (which use Microsoft’s internal APIs) but not through eM Client.

Solution:

If you need to create Teams online meetings in eM Client, you must use a Microsoft 365 work or school account that has Teams properly enabled and licensed.

Personal Microsoft accounts cannot be used to create Teams meetings via eM Client (or any third‑party application) because the Graph API does not support this scenario.

If you need to show our support team what’s happening on your screen, a screen recording can be more helpful than a screenshot.

Screen recordings on Android:

• On most Android phones:
  • Swipe down from the top of your screen to open the top menu and look for a “Screen recorder” button.
  • Tap it and “Start recording”. A few seconds later, it will start recording.
  • To stop the recording, tap the square button on your screen. The video will be saved to your Gallery app.
• To share in a new message:
  • Tap the Share button (three connected dots).
  • Select eM Client or another email app. A new message will open with the video attached.
• To share in a reply:
  • Open the reply you’re writing and add the video as an attachment (a paperclip icon).

Screen recordings on iOS:

• On most iOS phones:
  • Open Settings > Control Center > Customize Controls. Tap the plus sign next to Screen Recording.
  • Tap the gray Record button. Three seconds later, it will start recording.
  • To stop the recording, tap the red Record button. The video will be saved to your Photos app.
• To share in a new message:
  • Tap the Share button (a box with an upward arrow).
  • Select eM Client or another email app. A new message will open with the video attached.
• To share in a reply:
  • Open the reply you’re writing and add the video as an attachment (a paperclip icon).

Looking for how to record your screen on your computer?

If you need to show our support team what’s on your screen, taking a screenshot is the easiest way.

Screenshots on Android:

• On most Android phones:
  • Press the Power button and the volume down button at the same time.
  • Or: swipe down from the top of your screen to open the top menu and look for a “Take screenshot” button.
  • The video will be saved to your Gallery app.
• To share in a new message:
  • Tap the Share button (three connected dots).
  • Select eM Client or another email app. A new message will open with the image attached.
• To share in a reply:
  • Open the reply you’re writing and add the image as an attachment (a paperclip icon).

Screenshots on iOS:

• If your iPhone uses Face ID:
  • Press the side button and the volume up button at the same time.
• If your iPhone uses Touch ID:
  • Press the side button and the Home button at the same time.
• To share in a new message:
  • Tap the Share button (a box with an upward arrow).
  • Select eM Client or another email app. A new message will open with the image attached.
• To share in a reply:
  • Open the reply you’re writing and add the image as an attachment (a paperclip icon).

Looking for how to take a screenshot on your computer?

In April 2026, Microsoft made changes to the AirSync protocol. Because of this, some free and personal Outlook accounts can no longer send messages in eM Client 9. This version uses AirSync protocol for sending by default, so you may see the following errors when trying to send emails:

• VersionNotSupported
• The input string '' was not in a correct format.
• Invalid namespace Meeting Response

If you want to keep using version 9, you can switch the sending protocol from AirSync to SMTP.

On Windows:

Close eM Client. Download and run this configuration file to update the Windows registry.

You can also change it manually if you prefer:

• Run REGEDIT in Windows Start menu
• Navigate to HKEY_CURRENT_USER\Software\eM Client
• Right-click > New > DWORD and name it UseAirSyncSendMail

On macOS:

Close eM Client. Open Terminal and run this command:

defaults write com.emclient.mail.client UseAirSyncSendMail -bool FALSE

After switching to SMTP, open Menu > Accounts (or eM Client > Accounts on macOS) and disable AirSync under Services. This stops the errors, but Outlook calendar and contacts will no longer work. You can use the local calendar and contacts or add these services from another provider.

Gmail enforces strict daily bandwidth limits to protect its infrastructure and prevent abuse. This restriction can happen during intensive syncing, large mailbox downloads, or frequent send/receive actions. If your account exceeds the number of requests allowed for that period of time, Gmail will apply a limitation known as “throttling”. The restriction is only temporary and will be lifted automatically after a day.

You can also try to restrict the amount of data downloaded into eM Client.
Go to Accounts and under the IMAP tab of the affected Google account, disable download for offline use or limit the time period of messages you synchronize to decrease the amount of data downloaded at the same time, at least temporarily. 
You can try increasing the time period over the following days if you need the full message history downloaded locally.

If throttling continues for an extended period of time even with these precautions, there might be additional issues on your email provider's side. In that case, please report this to the Google support team so they can look into it or reconsider these limitations. 

How can you tell if your account is being throttled?

Throttling is usually visible in the IMAP diagnostic logs. A snippet of what it looks like in the logs:

01: A3 OK Success [THROTTLED]

01: A4 NAMESPACE

01: * NAMESPACE (("" "/")) NIL NIL

01: A4 OK Success [THROTTLED]

01: Detected server type: Gmail

01: A5 ENABLE CONDSTORE

01: * ENABLED CONDSTORE

01: A5 OK Success [THROTTLED]

The -ERR NTLM Failure error is usually caused by a mail server configuration issue.

Some mail servers advertise NTLM as a supported authentication method even though NTLM authentication has been disabled. When eM Client attempts to use it, the server rejects the connection and returns this error.

The proper fix is to update the mail server configuration so it no longer advertises NTLM if it is not supported. Please contact your mail server admin or email provider to have this corrected.

If the server cannot be updated, our support team can provide a workaround.
Before contacting us, please enable logging for the affected account under Accounts > Diagnostics, save the changes, restart eM Client, reproduce the issue, and then send us the logs. You can find the log file location under Settings > Advanced. The workaround needs a specific alternate authentication method to be used, so we cannot provide advice without the log.

On some Windows devices with both eM Client and Microsoft Outlook installed, Outlook keeps showing this message:

Either there is no default mail client or the current mail client cannot fulfill the messaging request. Please run Microsoft Outlook and set it as the default mail client.

When you click OK or close it, the error window reappears. It seems to have started after eM Client 11 was installed or updated, but the issue is a bug in specific versions of Outlook/MAPI.

How to fix it

Before you start, shut down both eM Client and Microsoft Outlook.

Option 1: Enable legacy MAPI registration

This fixes the error in most cases. You can apply it with our registry file or by hand. Both have the same result.

Method A: Use our registry file (recommended)

1. Download the fix here: AlwaysUseLegacyMapiRegistration.reg
2. Double-click the downloaded file.
3. If Windows asks whether you want to allow the app to make changes, click Yes.
4. When Registry Editor asks you to confirm adding the information to the registry, click Yes, then OK.
5. Start Outlook and check whether the message still appears.

Method B: Create the registry value manually

1. Press Windows + R, type regedit and press Enter.
2. Go to HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail
3. Create a DWORD (32-bit) value named AlwaysUseLegacyMapiRegistration and set its value to 1.
4. Close Registry Editor, start Outlook and check whether the message still appears.

Option 2: Use the extended registry file (if Option 1 doesn't help)

If the message still appears after Option 1, this file goes a step further. It:

• Sets Microsoft Outlook as the default Simple MAPI mail client, replacing the packaged (MSIX) mail registration.
• Turns on AlwaysUseLegacyMapiRegistration for both 64-bit and 32-bit applications.
• Removes any per-user mail client override, so the system-wide setting above is applied.

1. Download the fix here: DisableEmMapi.reg
2. Double-click the downloaded file.
3. If Windows asks whether you want to allow the app to make changes, click Yes.
4. When Registry Editor asks you to confirm adding the information to the registry, click Yes, then OK.
5. Start Outlook and check whether the message still appears.

Please note
We have observed that Option 1 fixes most cases of this error, but not every single one. If it doesn't help, try Option 2.

If one of the registry fixes worked once but the error comes back after some time, for example, after a Windows or eM Client update, simply run the same file again.
Unfortunately, MSIX installation will reset the registry each time, so if you need to keep using both eM Client and Outlook, you will need to re-run the registry file after every update.

Still seeing the message?
If the error persists after trying Options 1 and 2, please contact our support team at [email protected] and include:

• Your version of eM Client from Help > About
• Your version of Microsoft Outlook (for example, Outlook 2019, 2021, 2024 or Microsoft 365)
• Any add-ins or plug-ins you use in Outlook (for example, calendar or contact sync tools)
• A screenshot of the error message

When you add a Microsoft 365 work or school account to eM Client 11, Microsoft might show the "Need admin approval" dialog without giving you an option to continue. This happens in organizations that don't allow users to approve third-party apps on their own. eM Client 11 connects through Microsoft Graph and needs new permissions, so it must be approved again, even if your organization approved eM Client previously.

To ensure all permissions are added correctly, send this link to your administrator:

https://login.microsoftonline.com/organizations/v2.0/adminconsent?client_id=e9a7fea1-1cc0-4cd9-a31b-9137ca5deedd&redirect_uri=https%3A%2F%2Femclient.com%2Foauth2&state=graph-only&scope=offline_access%20openid%20email%20profile%20https%3A%2F%2Fgraph.microsoft.com%2FUser.Read%20https%3A%2F%2Fgraph.microsoft.com%2FUser.ReadBasic.All%20https%3A%2F%2Fgraph.microsoft.com%2FMailboxSettings.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FMail.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FMail.ReadWrite.Shared%20https%3A%2F%2Fgraph.microsoft.com%2FMail.Send%20https%3A%2F%2Fgraph.microsoft.com%2FMail.Send.Shared%20https%3A%2F%2Fgraph.microsoft.com%2FCalendars.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FCalendars.ReadWrite.Shared%20https%3A%2F%2Fgraph.microsoft.com%2FTasks.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FContacts.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FShortNotes.ReadWrite

The administrator opens the link, signs in with an admin account and clicks "Accept". After that, add your account in eM Client 11 again and it should go through.

Note for administrators:
Please use this link instead of "Grant admin consent" in the Microsoft Entra admin center. The admin center doesn't list all the permissions eM Client 11 needs, so consent granted there may not work.

1. If you’re getting an error message, please enclose a screenshot of the error.

2. Send us the whole content of the ‘Log’ tab.
If an error appears, you can access the log by clicking on the third tab in the same window as the Error. If no error appears, go to Menu > Operations, click the 'Copy log' button and paste the log (Ctrl+V) in a message to us.

3. Send us the full number of the version that you’re using (you can find this information in Menu > Help > About).

4. Try to remember what changes you’ve made in eM Client or in your system before the problem started and describe them to us.

Submit the report via one of our Support options or send it to [email protected] (if you're still using the Trial version) and we’ll do our best to resolve the issue as soon as possible.

If you get an error indicating that your database is corrupted, the fastest way of getting eM Client running again is to restore your data from a backup.

This option will be available either from the window informing you about the results of the database check or from eM Client’s interface in Menu > File > Restore.

If you can’t access eM Client to restore the data, please follow the information below on starting with a new database to open the program.

To start with a new database, turn eM Client off and rename the "eM Client" database folder (default location is in hidden folders AppData\Roaming, the whole path is C:\Users\%username%\AppData\Roaming\eM Client) to e.g. ‘eM Client old database’.

Please note that eM Client must stay turned off during this process. Check for eM Client or mailclient.exe in the Task Manager and if you see a process with either of these names, end it before you proceed.

If you do not have a backup but still have all your data saved on the server, you will have to start with a new database, re-create your accounts from scratch and wait until the data is synchronized again.

The special folders in Favorite folders collect messages from all accounts. If there are copies of the same message it can mean the message is copied into more folders or among more accounts.

Common causes for this include:

• Duplicate setup - make sure each of your accounts is set up only once in Menu > Accounts, or all messages will appear twice in Favorite folders
• Rules - do you have any rules that are meant to copy incoming messages? Check the Menu > Rules to make sure that there isn't a rule creating unwanted copies.
• Forwarding - do you perhaps have a server-side forwarding set for one of your accounts? If you don't want messages from one account to always be forwarded to another, check your server rules, for example through webmail

Note: In eM Client 6 this problem also sometimes happened with Gmail accounts, which keeps a copy of each message in All Mail folder and also created copies in Important and Starred labels.
Since eM Client creates a separate folder for each label, emails that have multiple labels attached to them will have multiple copies saved. The only workaround for that issue is to disable the showing of redundant labels like "Starred" and "Important" in IMAP. You can find this option by opening a web browser and logging in to Gmail. Click on Settings, and then go to the tab at the top called "Labels".

Since eM Client 7.0 we have adapted Gmail's internal structure. All messages have just one copy in the All Mail folder and other folders are just assigned labels.

It’s important to realize how eM Client works with IMAP: it only downloads message headers by default to make synchronization more efficient and to save space on your device.
Messages themselves are fully downloaded once you click on them to show their content in eM Client. Thus, eM Client cannot search in the bodies of all your messages by default.

If you’d like to search inside the messages, you can download your messages for offline use.
This setting is available in Menu > Accounts - the account that you’d like to download the emails for - IMAP tab - Offline - "Download messages for offline use".
You can also include images and attachments (if you want to search inside text attachments).

POP and EWS accounts download full messages automatically.

We have enhanced the IMAP certificate checks so this is an expected result when your certificate name does not match the hostname. Please either use the correct certificate or match the server address found in your account settings (Menu > Accounts > the relevant account - IMAP tab - Host) with the one in the current certificate details.

If you are redirected on the server and the names can’t match, you can also choose the possibility to connect with the current settings and remember this choice.

When setting up a POP3 account using the automatic or manual account setup, you can choose between creating a separate folder tree in the left pane for your POP3 account, or you can have your items synchronized with the default local folders tree.

Both options will store your emails locally as POP3 accounts do not keep your items synchronized with the server and are only used to download new data. Having the account in the left pane will allow you to move the account in the list of your accounts, having it listed under local folders will, on the other hand, reduce the number of listed accounts.

This choice cannot be changed after the setup, you will need to set up the account anew. Be careful not to accidentally remove your messages when doing so, you can always create both setups at once, copy your messages and then remove the unwanted setup.

Microsoft has unfortunately decided to stop supporting Skype for 3rd party applications so this feature had to be removed from eM Client. eM Client does not provide VoIP functionality, but clicking on the phone number in the Contact section of the Sidebar (on the right side of the main eM Client window) results in the standard call-to action, which should detect your default VoIP app and dial the number.

Unfortunately, Facebook has decided to quit Facebook Chat support for third-party applications as of April 30th, 2015. Therefore, this functionality has been removed from eM Client as well.

For IMAP accounts eM Client by default only downloads the headers of incoming messages and the body content is downloaded once you open the message's details.

While the startup synchronization is being processed by your server, it's possible the request for downloading body content may have timed out and can be run again once the folder sync is finished.

To avoid this, try to enable the "Download messages for offline use" on your account or one of your folders – for example, your Inbox.

To do so, navigate to your account settings, IMAP, and check the option to download messages for offline use, or right-click your folder, navigate to its properties and enable the option for selected folders only.

This warning is a general connection error, and it can be caused by minor connectivity issues between the application and your mail server. It can occur when the server is not responding or if the number of requests is higher than usual and the server is unable to respond while the request is valid.

Don't worry though – eM Client should be able to automatically reconnect if the connection error is thrown unless there's a real problem on the server.

You can find more details on what causes this connection issue in the third tab called Log in Menu > Operations. If you need help analyzing the problem, get in touch with our support.

This window is a normal step of Gmail accounts set up, as can be seen in our step-by-step Gmail/G Suite setup on our website.

It's part of Google's authentication called oAuth, where instead of giving the external application (eM Client) your password, you just give access from your Google account settings.

So, log in with your Gmail account and allow access for eM Client by clicking on "Accept" on the second browser page right after you log in to the browser.

eM Client will be granted an authentication token that you can revoke at any time using your online Google accounts settings.

Read more in our blog: OAuth authentication with Gmail

If you try to upload or change an event, task or contact but an error message pops up with the reason described in the message (e.g. invalid value, missing or empty field) it means that there is an invalid item that you're trying to synchronize with the server.

Try to delete the local changes to stop the synchronization – if this cannot be done manually or the error message cannot be closed (or keeps reappearing) it might be best to clear the local cache memory in eM Client for this account and download the correct data from the server.

Simply right-click the affected folder (calendar, contacts folder, etc.), select Properties and open the Repair tab. Click the ‘Repair’ button and wait for the resync to finish.

Blacklist is managed in menu > Settings > Mail > Blacklist and whitelist. The ‘Manage Blacklist’ button will open a window where you can add or remove any email addresses or domains.

Local blacklist is available to everyone. From eM Client 10.1, we also offer support for server-side Blacklist as well as Whitelist for IceWarp and SmarterMail accounts.

You can read about the Blacklist and Whitelist feature in more detail in our blog post here: eM Client Blacklist & Whitelist

eM Client 9 and older:

You can view and manage the Blacklist rule in menu > Rules on Windows or in Tools > Rules on macOS. Just select the Blacklist and click the 'Edit' button.

A new window with all the domains and addresses in your blacklist will pop up and you can add new items or remove any of the email addresses and domains already in it.

If the program somehow switched to a language you do not understand, do not worry!

The buttons are located in the same place for all localizations, so follow these screenshots to find your way to the language settings:

1. On Windows: Open menu > Settings in the main window. Menu is in the top left corner of the program, Settings is a 9th item on the list in the drop-down menu. On macOS: Open eM Client > Settings, the 9th item on the list in the drop-down menu.

2. This will open the Settings window. Here you want to open the General > Language section. General is the very top section while Language should be the 3rd one in the list below. 

3. Then just select your preferred language and press Ok.     

The Operations log can be very useful for troubleshooting, as it contains information about the Operations that were done during this run of the application. If there is an error message the Operations log might contain more detailed information about the error itself.

If an error message already popped up, the Log can be found in the third tab of the same Window. Otherwise, you can open this window manually in Menu > Operations. The Log is in the third tab of this window.

Simply click the Copy log button and then paste the text into a text editor (Notepad, MS Word, ...) via the Ctrl+V shortcut.

You can then search for your error message there in case the error details made the reason self-explanatory or you can send this log to the support so we can analyze it and provide advice.

Support options are described on our website in Support overview section. 

LEGACY OPTION

In older versions the Copy log button is not available, so you will need to copy the log manually.

• Open the Log tab and then click inside, to select a single line
• Press Ctrl+A keyboard shortcut to select all the lines
• Use Ctrl+C to copy the content
• Open a text editor (Notepad, MS Word, ...) and use Ctrl+V to paste the log there and then send it to support.

Unfortunately, Gmail does not forward the information about the label color through IMAP protocol, so eM Client cannot load the exact same colors and assigns random ones instead.

However, if you go to Menu > Tags and create a new tag with the same name as your Label, you will be able to select your own color in eM Client.

This workaround will work for all top-level Folders/Labels, not subfolders.

This is, unfortunately, a common confusion, as there are actually two different settings for changing your font style in eM Client. One is your preferred style for reading messages and the other for writing/composing a message.

1. Menu > Settings > Mail > Read

The Preferred Style setting in this section will be applied to the messages you read, if they use Plain text. Plain text format does not have any set "visual" formatting, so you can apply your own.
This way you can make the font easier to read for you.

The setting will not be applied to HTML messages, which do have set formatting.

2. Menu > Settings > Mail > Compose

The Preferred Style in this section will be used for writing all your messages.

Attention: These solutions can only work with eM Client 8.0 - 8.1, they will not work for legacy versions of eM Client. eM Client 8.2 and newer do not need this solution, as it is included natively.

eM Client supports MFA/oAuth login, but the pop-up window for this authentication method will not be allowed to be used by default on your device.
That is why the login method will not work natively for now, but we have prepared workarounds to help you out:

eM Client for Windows

• Download the attached registry file in this article.
• Run it while eM Client is still closed and confirm the changes it will make.
• Run eM Client and use the automatic setup to set up your accounts with oAuth.

If you'd like to add the needed registry key manually instead of using our provided file:

• Run Regedit
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Add the DWORD item AllowExchangeOnlineOAuth and set its value to 1
• Then run eM Client and use the automatic setup to set up your accounts with oAuth.

eM Client for MacOS

• Open the Terminal
• Execute this command:
• defaults write com.emclient.mail.client AllowExchangeOnlineOAuth -bool TRUE
• Run eM Client and use the automatic setup to set up your accounts with oAuth. 

WARNING: If you use this work-around please make sure to disable the 'Offline Address Book' service during the last step of the setup.It is not compatible with the oAuth setup and could cause additional problems with the setup.

Upon upgrading to eM Client 8, all your folders were “hidden” by default under a folder called 'More'. This was to give you a fresh start with your folder management and make the interface more streamlined.

To remove items from the More folder, simply drag them out of it. Once there's nothing in the folder, it will disappear. To add items back, simply right-click an item and select Hide.

Alternatively, you can manage which items are hidden under the More folder or shown on your folder list by right-clicking your email account name in the folder list and selecting Show/hide folders.

Most users nowadays have high-speed internet connections and therefore an explicit progress bar for sending messages was no longer necessary in Version 8.

However, if you still want to monitor the progress of your sent emails and updating folders, you can open the Operations window by going to Menu > Operations.

If you want the Operations window progress bar to always be displayed as you send and receive messages, you can turn on this feature under Menu > Settings > General > General > Operations Window and select the box for Show window on send and receive.

When you go to type in a name in the To: section, if there is an X button on the right side in the suggestion list, then it can be deleted from the history of recipients via click on that button.
Otherwise, the unwanted contact must be deleted from your address book or the messages sent to this email address from the Sent folder.

You can also adjust your suggested recipients list by going to Menu > Settings > Mail > Compose > Email Address Suggestion.

Suggestions based on messages in Sent folders and Recipients history based on your use in eM Client can be turned off; suggestions based on your saved Contacts cannot be disabled.

This is a known issue with some Gmail events and system notifications, you can resolve this by unchecking the Use system notifications box in Menu > Settings > General > Notifications.

eM Client uses external service for translations, so it has to pay for each translation made through its interface. For this reason, Free license users have limited access to this feature.

There are no limits for paid licenses.

Read more in our blog: On-the-fly Email Translation in eM Client and in the Documentation: Spell-checker and translator

Google unfortunately doesn’t support recurring tasks, the information about recurrence is saved locally in eM Client. If you remove and add your account again this information is lost, because the local data has been cleared and the newly synchronized data from the server does not contain the recurrence information.

Some servers might not support distribution lists and can therefore try to change the list into a regular contact, leaving only the first email address. To prevent this, please save your distribution lists into eM Client’s Local folders. The list will not be synchronized but you will be able to use it from the application’s interface.

Read more in the Documentation: Distribution List

Go Daddy servers are rejecting the version of Chromium in our application, so the secure OAuth login in our native browser window during the account setup could not finish. The error messages that shows up when this happens is:

Your Browser is a bit unusual...
Try disabling ad blockers and other extensions, enabling javascript, or using a different web browser.

We have created a fix version which will use your default web browser instead of our native window for this authentications. Please download this version here: https://www.emclient.com/dist/v8.2.1509/setup.msi

One of the largest certificate issuers Let’s Encrypt had their root certificate validity end on 30. 9. 2021. In case your validity has not been renewed, an error might occur with eM Client licensing and other programs as well.

How to check your certificate validity in Windows?

1. Navigate to the Start menu in Windows and type certmgr
2. Open the Certificate Manager app by pressing enter and allow changes
3. In the left window navigate to Third-Party Root Certification Authorities
4. Click on the file Certificates that shows up
5. Go to the right side and find ISRG Root X1 in the ‘Issued to’ column- it is ordered alphabetically
6. Check the expiration date in the third column

Now, in case your certificate has validity to 30.9.2021 it means it is past due. 

Here is how to solve the problem.

1. Download the attached file 'ISRG Root X1.cer' and open it on your PC
2. A window pops up, click on Install Certificate
3. Click Next on the following screen
4. Check the option to Place all certificates in the following store
5. Click Browse and select Trusted Root Certification Authorities and click OK
6. Click on Next and then Finish to import the certificate

How to solve this issue on Mac?

Remove the old ISGR Root X1 certificate from your Keychain and then download the attached file 'ISRG Root X1.cer'

The Unauthorized License Detected warning should show up if you are using an illegal version of eM Client, which is detected by your System checking eM Client's program file signatures. Recently, some users encountered this warning even with a valid program and license, because of an outdated certificate in their device.

In the current versions released after January 2023, eM Client now uses Azure Code Signing to sign its program files. The Windows version of the app is signed using a Microsoft certificate to prove its validity and safety when used on Windows devices.
So if you encounter this warning, please make sure to have the latest Windows update on your device installed.

If you do have the latest updates, you can check and/or install the missing certificate directly.

Go to the eM Client installed program files, default C:\Program Files (x86)\eM Client.
Find MailClient.exe and open its Properties.
Open the Digital Signatures tab.
Click the eM Client s.r.o. signature in the list and open Details.
Check the signature here.
If it's shown as invalid, select the Microsoft signature at the bottom and open its Details.
Then click View Certificate button and check the Certification path.
if there is any Microsoft certificate missing (a red X over the certificate icon), install it or add it to trusted certificates.

You can find Microsoft certificates in their repository here: https://www.microsoft.com/pkiops/docs/repository.htm
Search for the name of the missing certificate, download it, and when installing it make sure to select the folder (store) manually and save it into Trusted Root Certificates Authorities.

That should resolve the issue - restart your device and start eM Client again.

For eM Client 9.2.1222 and older you can use this solution:

To check if you are affected by this problem, please check this webpage: https://trusted-root-g4.chain-demos.digicert.com/
If the page shows a warning, you need to update your root certificate DigiCert Trusted Root G4.

This can be sorted by installing available security updates for your Windows or you can find the updates manually here: Support for urgent Trusted Root updates for Windows Root Certificate Program in Windows

You can also manually download the certificate here: 

DigiCert Root Certificates | DigiCert.com

Direct download for DigiCert Trusted Root G4 | DigiCert.com

To avoid similar issues in the future, make sure you have the Windows Root certificate AutoUpdater active.
This can be changed in Windows registry directly in HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\SystemCertificates\AuthRoot
Just make sure the DisableRootAutoUpdate key is set to 0.

If the issue is not resolved even after manually updating or re-installing the missing certificates, you can reinstall the app in case the issue was in the corrupted program files.
Follow these steps:

- Uninstall eM Client (do NOT delete your database)
- Make sure the eM Client folder and files are gone from C:\Program Files (x86)\eM Client or C:\Program Files\eM Client
If not, delete them manually.
- Then download and install the app for your licensed version from an official file downloaded from our website: https://www.emclient.com/release-history

In June 2022 Google discontinued their support for less secure login methods for their email accounts. The solution to this is to set up your account anew using the secure OAuth method.
Please read more here: Google ‘less secure apps’ access and what it means for eM Client

If you experience problems with eM Client not behaving as default mail client for opening mail files, using Mailto links from web, etc. there might be a specific default setting missing in your system.
The best way to resolve it is to go to your System settings > Apps and then 'Set defaults by app' (Windows 10) or 'Default apps' (Windows 11).

From the list of installed apps select eM Client and then assign all available file and link types to make eM Client function fully as a default app for all email and calendar functions.

If you experience issues using the Send to > Mail recipient function in Windows, the attached registry file can help - simply download it and run it.

If eM Client is missing from your system "Share" menu, it is most likely missing from the location in System Settings/Privacy & Security/Extensions/Sharing

Please open the Terminal and run this command to add back any missing apps:
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -seed

If you set a custom location for your database and the location is not available (for example external drive that is disconnected), you might have trouble running eM Client.
To delete the custom storage location setting open the Terminal and run this command:
defaults delete com.emclient.mail.client DBLocation

If you encounter this error with Word files specifically, the issue might be the Privacy settings in your Microsoft Office apps.

Disable all the "Connected Experiences" in the Privacy Settings of Word (or another Office program this applies to), and you will be able to attach open Word files again. 

On macOS and iOS, some eM Client users experienced SMIME certificates error “unknown revocation status.” This also affected some HTTP services, such as the automatic translation.

This is caused by the fact that Apple’s system does not always properly handle certificate revocation checks after Let’s Encrypt deprecated Online Certificate Status Protocol (OSCP) method in favor of Certificate Revocation Lists (CRL). We suspect that Apple does not take CRL into account at this time and since OCSP is no longer available, the status is left "unknown."

eM Client offers a setting, IgnoreUnknownRevocationStatus, to control this behavior now, which has 3 options:

The default behavior since eM Client 10.3.2298 will now ignore this specific error, but you can use these commands to change it:

To explicitly allow SMIME certificates to work, run this command in the terminal:
defaults write com.emclient.mail IgnoreUnknownRevocationStatus -int 1

To Enforce strict validation (this might also block other HTTP services, including eM Client's translation, QR Import, EWS Servers and more):
defaults write com.emclient.mail IgnoreUnknownRevocationStatus -int 0

To return to default behavior:
defaults delete com.emclient.mail IgnoreUnknownRevocationStatus

To speed up email address suggestions when composing an email, go to menu > Settings > Mail > Compose and disable “Use all recipients from Sent folders for suggestions” under Email Address Suggestion.

Depending on your email history, this option can cause a significant delay since the app needs to load recipients from Sent folders across all your added accounts each time you're composing an email.

Disabling it should resolve the issue, but if you still experience slow address suggestions, you can also try using the Clear recipient history button or deleting specific irrelevant addresses via the Show recipients button. If you only want to use your Contacts for the autocomplete, disable “Store composed mail recipients for suggestion”.
Read more on this feature on our blog.

No longer possible.

With the recent changes on Microsoft servers, the IMAP protocol for Outlook/Hotmail/Live/MSN/etc. accounts can be unusable for some external applications at this time.

Please set up your account as Exchange.

• Download the attached registry file in this article.
• Run it while eM Client is still closed and confirm the changes it will make.

If you'd like to add the needed registry key manually instead of using our provided file:

• Run Regedit
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Add the DWORD item AllowExchangeOnlineOAuth and set its value to 0
• Then run eM Client 

To set up the actual account:

• Go to Menu > Accounts.
• Click the '+Add account' button.
• In the New Account window select Mail > Exchange.
• Use your Microsoft mail address for both the Email and Username fields. 
• Finish the rest of the setup
• Delete or disable your previous IMAP setup.

NOTES: Detection of Exchange setup might take longer than usual, but unless an error pops up, let the configuration finish.

If you use 2-factor verification, you might need to create and use an App password for eM Client.

Exchange Web Services protocol will synchronize your Mail, Contacts, and Calendar - you do not need to worry about any data loss because this information is saved on your mail server.

If you upgraded from eM Client 6, your data hasn't been actually lost - you just accidentally skipped database migration.

Since eM Client 7, we have created a completely new database structure for more efficient data storage, so the data cannot be just loaded from the old database as was possible in the past.

To migrate your data manually please use the Menu > File > Import.. > Import from eM Client 6 option.

If you upgraded from eM Client 7, the database should be upgraded automatically, since eM Client 8 keeps to the same model and can upgrade these files automatically, no migration is needed.

In this case, the issue might be with your storage location - make sure that the storage folder in Menu > Settings > General > Storage is pointing to the correct location where your eM Client 7 database was stored.

Please try the following steps to get rid of any 'ghost' messages:

• Turn off Conversations (Menu > View > Conversations > Disable Conversations)
• Close eM Client
• Open RUN function from the Start menu
• Run the command "C:\Program Files (x86)\eM Client\MailClient.exe" /dbrepair
• (For MS Store version of eM Client the command is eMClientStore.exe /dbrepair )
• Wait until the database check is completed
• Turn eM Client on
• You should then be able to set any Conversations setting you prefer.

For IMAP and Exchange accounts only:

• If that doesn't help, please right-click on the folder that the messages are in, select Properties > Repair and click the Repair button.
• This will prompt the resynchronization of this folder from the server and should reset its data.
• You can also try removing your account from eM Client and then adding it again in Menu > Accounts.

Please note that all locally stored data will be lost, but if you have your data on the server, that shouldn't be of concern.

You can make a backup just to be on the safe side through Menu > Backup.

• go to Menu > Tools > Settings > General > General
• Scroll to Operations window
• uncheck the option to Show window when an error occurs

Last update on this post has been made on May 12th, 2017

This is a known issue with selected Yahoo servers because Yahoo does not officially support subfolders at all.

That is why the subfolders created in eM Client can disappear after synchronizing with the Yahoo server. The server will clear them out.

We suggest only using top-level folders in Yahoo to make sure no messages get lost.

This issue started happening in eM Client 7.0 when we changed the way we work with Gmail. Since we started supporting Gmail labels and folder structure, all labels are synchronized.
And one thing that was not visible before (and might not be visible in other clients) is that Gmail assigns the 'Important' label to all messages synchronized through IMAP.

In eM Client 8.1 we added a workaround in the Menu > Accounts section under the IMAP tab.

Under the Tag section you will find the Show Important tags option and you can select to either show it based on Gmail's settings, Always show it or to Never show it. 

LEGACY OPTIONS

In older versions, you need to go to your Gmail settings in your web browser and create a filter that will remove the Important label automatically from each message.

To achieve this, go to Gmail webmail, open Settings > Filters and Blocked addresses. Create a new filter where all messages received by your email address will never be marked as Important.

Screenshots of such filter setting can be found below:

Note: You can either apply the filter directly to all previous conversations or open the Important folder/label and manually select all messages to remove the Important label

Microsoft has officially ended support for Windows XP on April 8, 2014.
Unfortunately, this means that the security protocols from the last service update are no longer up to the current standard.

So when you try to activate the license after the eM Client trial, you will encounter an error message instead, because the request sent from Windows XP, unfortunately, doesn't arrive at our licensing system.

A problem has occurred when contacting the licensing server:

The underlying connection was closed:  an unexpected error occurred on a send.

We have created a compatibility version for XP which allows the connection, but please be aware that this version will not be updated in the future.
Please send us a message to [email protected] if you are interested in this version.

Users of BTinternet email accounts have recently seen a variation of these errors:

[IMAP] Cannot open folder ... ([Clientbug] Select additional arguments found after last expected argument)

[IMAP] Cannot open folder ... (unrecognized extra arguments to SELECT command)

We have analyzed the issue in detail, including IMAP logs provided by some of our users and our developers concluded that it's a server issue that can't be fixed on our side, unfortunately.

It seems that the BT updated the feature on their back-end servers but didn't adapt the proxy servers which report the errors. It seems that BT is continuously changing the settings and that's why sometimes the account reset helps but later on the issue reappears.

Some tweaks to the settings seem to help though, these are solutions provided by our users:

"A bit of research reveals that BT uses two versions of mail - BT email and BT Yahoo email. See here

http://bt.custhelp.com/app/answers/detail/a_id/57483/~/im-not-sure-if-ive-got-bt-mail-or-bt-yahoo!-mail

By logging into the desktop version of BT email you can see which version you have got. It transpires I have BT Yahoo mail. I have set the email up using BT Yahoo settings and it is now working again. Something must have changed on BT's side. So if you get this query again this should be the solution."

Another tip that seems to help is filling in the manual option for credentials under the IMAP tab in Menu > Accounts. Open this section and open the IMAP tab for your BT account. Insert your credentials into "these credentials" fields and save the settings.

Also, if your username is set anywhere as just the user part, make sure to change it to full address - ie. if the full email address is [email protected] make sure the user name is set to "[email protected]", not just "example".

Update: NTLM is now supported in eM Client 8.2 and newer

In case you're trying to set up an Exchange account in eM Client for Mac and you're getting pop-ups with failed authentication, then your mail server most likely requires an NTLM authentication, which is currently not supported in eM Client for Mac.

We are aware of the problem and are collaborating with Microsoft on a solution that will solve this once and for all.

A possible workaround is setting the account up with IMAP protocol manually via eM Client > Add account > Mail > Other or ask your mail server administrator if there are some other authentication methods available for Exchange protocol on your server.

If you use Google or Yahoo accounts your accounts might have stopped synchronizing after the upgrade. This is most commonly caused by external apps like Antivirus, Firewalls, VPNs, etc. which are blocking the new version of eM Client for your safety because the program is new and therefore not in any trusted databases of these programs.

We have seen this often happen with Avast, Kaspersky and AVG, though others could cause the same problem.

Adding eM Client to exceptions in these apps and disabling any mail shields should resolve the issue.

We also recommend reporting this to the provider of your security app, so they can update their records and not block eM Client in the future.

Previous versions of eM Client had several important features (such as Settings, Operations and Accounts) which were embedded under Menu > Tools. Therefore, a lot of our documentation and help articles written before the release of eM Client 8 in June 2020 have instructions that follow that pathway. With eM Client 8, we promoted some of these frequently used features to just be under Menu. Additionally, some features (such as Categories and Smart folders) have been renamed.

The release of eM Client 8 has brought enhanced search capabilities, including searching in the text of attachments and on IMAP and Exchange/Office365 servers. Sometimes though, searching through the mail server does not return correct/expected results, so it might be beneficial to turn off server search and search locally within eM Client instead.

To do this click on the down arrow v on the right side of the search bar and deselect Use server search if available. Also, while you’re in this search menu, double check that you’ve selected the correct search parameters, such as searching in All folders and searching for your keyword in the Subject, Sender, Recipients, Body and Attachments fields.

Read more in our blog: Search Like a Pro in eM Client

We believe that the slowness of the new version is likely due to the attachment indexation and folder syncing. You can try leaving eM Client running overnight so it can complete this process.

Alternatively, you can run the eM Client application with a disabled indexer by pressing the Windows key and R key at the same time and entering the following command:

"C:\Program Files (x86)\eM Client\MailClient.exe" --disable-attachment-indexer

(Unfortunately, there's not currently a similar workaround for Mac OS)

We’re also working hard on fixing the speed issue and bringing you better performance with future updates.

Generally, Pro Support is only available to Pro License holders for one year after their purchase, otherwise we direct Free users to our Support Forum.

However, since the new eM Client 8 was recently released, everyone is treated as a Pro user for a month and is contacting the Support Team for a large range of issues. This has greatly increased our number of new support tickets to 100s every day and created a backlog. Some of the issues are bugs that our users have caught and we can pass on the information to our developers to fix and make eM Client better for everyone.

We’re happy to help you and we promise that your ticket has not been forgotten or lost, but your patience is greatly appreciated during this time.

This is likely caused by the system notifications from your operating system. Try going to Menu > Settings > General > Notifications and disabling the "Use system notifications box". Sometimes the system notifications from Windows misbehave and don't work correctly.

When you disable them, the native notifications for the eM Client Application take over and are more reliable.

If you get the following error:

[Google Contacts]Uploading item(s) to folder '[email protected]/Contacts' failed due to the following error: Execution of request failed: https://www.google.com/m8/feeds/contacts/default/full (Invalid request.)

The first thing you should know is that most of the "folders" of Google's mail, contacts, tasks, calendar, etc. are just a complex Tag system that's pretending to be folders.
When objects (messages, events, contact entries etc.) are without a Tag to sort them somewhere, strange things and errors start to happen. Understanding that will help you understand the rest of the explanation and the solution.

It seems that if you click the orange + New > Contact button then it will typically default to the root /Contacts folder, which is what's causing your error. If you're creating a new contact using that method, you must either select a Tag to apply to the folder or select a subfolder.

The way to change the default is to select any of the subfolders before clicking the orange + New > Contact button. Then it will automatically apply a tag to the contact and it won't trigger the error.

To fix the rest of your contacts that have this "No Tag" error, the easiest thing to do would be to go to the Contacts folder and sort all of your contacts by Tag in ascending order. This will cause all your "unsorted" contacts to appear at the top. Drag all of the unsorted contacts into any of your subfolders and this will apply a tag to them and stop the error. It could also be helpful to click the "select" option so that you can easily select multiple entries at once.

After uploading your Public Key to eM Keybook, you might have received a message saying:

Uploaded Public Key not Verified

Public Key John Doe for email address [email protected] was uploaded to eM Keybook, but has not been verified yet. Should eM Client keep monitoring for incoming verification emails?

This occurs when you have not yet checked your email to confirm that you would like to upload your Public PGP Key to eM Client. The message you should be looking for is called "Verification email from eM Keybook" and it will be sent from [email protected].

Furthermore, some email accounts (such as @seznam.cz, @yahoo.com, or @aol.com) have a problem if checking the message through normal means does not trigger the confirmation.

The workaround for this problem is as follows:

1. Right-click on the "Verification email from eM Keybook" message in your list of emails in your inbox and select "Save as" and then save the email as a .eml file.
2. With this .eml file you exported, go to your file explorer in Windows where you've saved it on your computer and open the file with eM Client.
3. When the .eml file is open click Menu > Message > Copy to Folder
4. Choose where you want to save a copy of the message in eM Client.
5. Navigate to where you saved the file within eM Client, and it should be displaying/working correctly and the verification will trigger.

On June 15th, 2021 Google phased out the Google Contacts API, which is a protocol we used for synchronizing Google contacts in older versions of eM Client. If you are still running one of these versions, you will encounter this error:

[Google Contacts] Synchronizing folder '[email protected]/Contacts' failed due to the following error: Execution of request failed:

(Contacts API is being deprecated. Migrate to People API to retain programmatic access to Google Contacts. See https://developers.goog.ecom/people/contacts-api-migration.)

We have switched to the current People API in eM Client 8.2, so if you are running any of the older versions, you need to either install the update (if your license is valid for eM Client 8) or upgrade your license and then install it.

You can of course keep using the older version if you prefer, but you will not be able to synchronize your Google contacts anymore, they will only be stored locally as they are.

To avoid the error pop-up, you can work around this situation by copying the contacts to Local Folders and switch off the Google Contacts service in Accounts settings.

UPDATE 9/30/2021: Microsoft has now fixed their OAUTH and the automatic setup will work again.

On September 24th, 2021 Microsft made some changes on their mail servers, which disabled OAuth login for the IMAP protocol on their accounts. Unfortunately, this affected all outlook.com, hotmail.com, live.com, msn.com and other free Microsoft account domains in our program, since we used this secure login method as default.
You can tell if your account is affected by a red triangle shown next to your account name. This account also cannot receive any new messages.

The workaround at this time is to set up the account anew manually either as Exchange or as Other (IMAP) to avoid usage of the IMAP-XOAUTH2 login.

Note: If you use 2-factor verification, you might need to create and use an App password for eM Client.

Manual IMAP setup (Other):

• Go to Menu > Accounts.
• Click the '+Add account' button.
• In the New Account window select Mail > Other.
• Insert your Microsoft account address
• Select IMAP.
• Insert these settings for Incoming server: imap-mail.outlook.com
• Outgoing server: smtp-mail.outlook.com
• Finish the rest of the setup
• Delete or disable your previous IMAP setup

Exchange setup:

• Download the attached registry file in this article.
• Run it while eM Client is still closed and confirm the changes it will make.

If you'd like to add the needed registry key manually instead of using our provided file:

• Run Regedit
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Add the DWORD item AllowExchangeOnlineOAuth and set its value to 0
• Then run eM Client 

To set up the actual account:

• Go to Menu > Accounts.
• Click the '+Add account' button.
• In the New Account window select Mail > Exchange.
• Use your Microsoft mail address for both the Email and Username fields. 
• Finish the rest of the setup
• Delete or disable your previous IMAP setup. 

When using an account that is running on an Exchange server provided by Microsoft, you can encounter this error:

Known Microsoft Exchange server error "User is authenticated but not connected" has been encountered on IMAP connection. This issue is temporary and should be automatically resolved by the server. If not, please contact your mail provider.

This error means that the authentication process for your account was succesfull, but for some reason the mail server is not giving eM Client access to the account data, so it cannot synchronize your messages into the app.

This can have a few different causes - sometimes it's a temporary issue that will go away on its own, but lately we had this issue reported with brand new outlook.com accounts that do not have IMAP protocol allowed.

• Sign in to your Outlook account via the webmail (https://outlook.live.com/)
• Go to Settings > Mail > Forwarding and IMAP > Login > enter your credentials again
• Enable Allow devices and applications to use POP and Allow devices and applications to use IMAP
• Save your settings and click the Refresh button.

If you already have IMAP allowed and the issue does not clear on its own, reach out to your admin or provider of the email account so they can fix the issue.

If this is happening with an email account that is set up using an Alias and not the Primary email address, try setting up the account anew using the primary email address to see if that resolves the problem.

If you use Windows system notifications for eM Client and eM Client is already running, you can encounter this error when trying to perform an action directly from the pop-up:

Communication with the previous instance failed. The other instance has to be ended in order to start the application.

This happens if you run eM Client in administrator mode, which is not compatible with Windows notifications. To avoid this issue, make sure to run eM Client as a regular user instead of 'as admin'.

Some users with the latest eM Client 9 for macOS might have encountered an issue where their messages never finish loading, even though clicking REPLY shows that the message text is available. We have tracked this issue to App-specific region settings, so if you have encountered this issue, please follow these steps:

1. Go to System preferences on your mac device
2. Open Languages and Region
3. Click on the Apps section
4. If there is any app-specific setting for eM Client, remove it from the list (especially if the region is set to Sweden or Norway).
5. Save this change and reload eM Client - your messages should show up correctly now.

Alternative, if there was no app-specific setting

1. Add eM Client here and set English as a language.

TLS 1.3 is the fourth version of the commonly used protocol for secure communication on the internet. Unfortunately, not all apps and systems can work with it correctly now, such is the case with Windows 10.

You can view which Windows versions can work with TLS 1.3 on this Microsoft page: TLS protocol version support

Gmail OAuth login on Windows 10
When TLS 1.3 is enabled, this can cause issues with the Google accounts OAuth - the authentication window will show up, but the setup can never be finished, the OAuth window will keep reloading and the eM Client app will not be able to connect to the Gmail server to synchronize your data.
The solution is to run the DisableTLS1.3.reg file attached to this article, start eM Client, and try the Gmail account setup again.

A similar issue can affect Kerio accounts when using Windows 10 as well. The solution is also to disable TLS 1.3 until Microsoft provides the required update to Windows 10.

This solution can also work if you encounter this error when sending or receiving an email:

"Cannot determine the frame size or a corrupted frame was received."

Update 3/2/2023: We have created an alternate workaround which uses AirSync instead of SMTP for sending emails, read more here. 
The new workaround is for eM Client 9.2, so if you use an older version of eM Client and do not wish to upgrade, please feel free to still use the workaround on this page.

In the past few days, users of @outlook.com, @hotmail.com and other free Microsoft email accounts might have encountered an issue when sending emails. 

[SMTP] MailClient.Accounts.AuthenticationAbortedException: Authentication aborted.

This issue is caused by a new problem on Microsoft's modern OAuth login method, settings up the account with an older version of the OAuth authentication in the meantime will work.

For the workaround, follow these steps:

Windows

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Download and run the registry file in this article - useoldoutlookcomflow.reg
  (this file can be downloaded at the bottom of this article, in the Attachments section)
• Open eM Client and log in using the OAuth window that pops up.

macOS

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Open Terminal and run this command: defaults write com.emclient.mail.client UseOldOutlookComFlow -bool TRUE
• Open eM Client and log in using the OAuth window that pops up.

Once Microsoft fixes this issue, you can either keep the older OAuth or remove the workaround with these steps, which are just the reverse of the previous ones:

Windows

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Download and run the other registry file in this article- removeoldoutlookcomflow.reg
• Open eM Client and log in using the OAuth window that pops up.

macOS

• Close eM Client.
• Revoke permission for eM Client in your Outlook.com account: https://account.live.com/consent/Manage
• Open Terminal and run this command: defaults delete com.emclient.mail.client UseOldOutlookComFlow
• Open eM Client and log in using the OAuth window that pops up.

Email provider GMX allows its users to enable more secure authentication for their accounts, the two-factor authentication - https://www.gmx.com/security/2fa

When you enable this additional security layer, you need an app password for other apps to login into your GMX account for you.
Most email service providers will use the same app password for one app, but GMX needs this password per each protocol/service you plan to use in a 3rd party application.

That means that for eM Client you will need three app passwords total - one to receive email via IMAP service, one to send via SMTP, and one to synchronize your contacts and calendars via CalDAV/CardDAV service.
Trying to use the same password on the whole account will result in rejected logins and might resolve in issues connecting to GMX Mail or GMX Calendar depending on where you use the app password.

Some users experience issues with their Exchange accounts on our mobile app, even though the same account connects correctly on desktop.

This is caused by incorrect NTLM implementation in the .NET platform, which our and many other applications use. This issue is usually triggered on Exchange accounts if you have "Extended protection" enabled on your server and it affects only mobile apps, not the desktop program.

Our developers have created a fix for .NET in its current version .NET 8 and .NET 9, and it should hopefully be merged soon.

https://github.com/dotnet/runtime/pull/102565
https://github.com/dotnet/runtime/pull/95898

Unfortunately, until that happens, we cannot provide any alternative solution - only wait for the fix to be merged into the .NET platform.

In December 2024, some Google accounts stopped showing the Birthday calendar after Google changed the way it handles birthday events. As a result, the eM Client app currently cannot show it.

Unfortunately, this means we'll also need to rework how this functions in eM Client. The possibility to display the Birthday calendar is set to be reintroduced in eM Client 11.

Update 10th July 2025: eM Client in versions 9.2.1628 - 10.3.2412 used AirSync instead of SMTP to send emails for free Microsoft email accounts - these are any accounts with domains @outlook.com, @hotmail, @live, @msn and other domains which Microsoft offered in the past, with all regional variants as well.
This change was made a few years ago when Microsoft broke SMTP Authentication for 3rd-party apps, making it impossible for us and many other apps to send emails.
You can read about this on our blog: https://www.emclient.com/blog/workaround-for-the-sending-issue-via-smtp-for-microsoft-outlook-com-accounts-570
Versions newer than 10.3.2545.0 now use SMTP again so the workaround below is no longer needed.

While AirSync does not suffer from the authentication issue at this time, Microsoft does not let it use ALL sending features - namely, any alias will revert to your primary email and send the email from primary address instead of your desired alias.
This, of course, does not affect users who don't need alias for these specific accounts, but if you need the alias feature to work correctly, you'll have to manually switch to SMTP.

Follow the steps below:

Windows

• Close eM Client.
• Open Start menu and type in REGEDIT and press Enter to open Windows Registry
• Go to Computer\HKEY_CURRENT_USER\Software\eM Client
• Right-click inside this section and create New > DWORD
• Name it UseAirSyncSendMail and save - this should set it to 0

macOS

• Close eM Client.
• Open Terminal and run this command: defaults write com.emclient.mail.client UseAirSyncSendMail -bool FALSE

Apple has stopped synchronizing tasks (which they call Reminders) using the standard CalDAV protocol starting with version iOS 13. 
Due to this change the tasks can no longer be synchronized not only with older versions of Apple apps, but also external apps like eM Client.
The sync via CalDAV still exists and works, and it will sync data between older Apple apps and other apps using CalDAV, and for example between two eM Client apps, but not with the current Apple applications.
You can read about this on this Apple support page.

eM Client does not use AIA (Authority Information Access) to fetch intermediate or root certificates on demand, and this is intentional for security reasons.

On Windows, trusted certificate authorities (CAs) are managed through the system certificate store. Outlook and some other applications can trigger Windows to fetch missing certificates from trusted CAs when needed. eM Client, however, only uses certificates already present in the Windows store. If an intermediate certificate is missing, it does not try to download it via AIA or force Windows to update its trusted root list (which is normally updated periodically through Windows Update).

This behavior is designed to prevent a type of privacy attack: a malicious sender could include a URL in the AIA field of their certificate pointing to their own server. If your mail client automatically contacts that URL to retrieve a certificate, the sender would immediately know you opened their email.

To avoid issues, make sure to import certificates with their complete chain (including intermediate certificates) into the Windows certificate store in advance.

In some cases, accepted invitations from your Gmail account may appear in eM Client but not in your Google Calendar. One common cause is the custom Google setting for automatically adding events from invitations.

Go to your web browser and open your Google Calendar settings. Scroll down to Event settings > Guest permissions and change it to Add invitations to my calendar "From everyone."

If any other setting is used, Google rejects the events added from eM Client, but does not show any errors or warnings. During synchronization, it seems that the server confirms that all is synchronized correctly, so unfortunately, there is little we can do on our end to avoid this issue.

However, other factors can also cause accepted events not to sync, so if adjusting this setting doesn’t resolve your issue, please contact our support team for further assistance.

In April 2026, Microsoft made changes to the AirSync protocol. Because of this, some free and personal Outlook accounts can no longer send messages in eM Client 9. This version uses AirSync protocol for sending by default, so you may see the following errors when trying to send emails:

• VersionNotSupported
• The input string '' was not in a correct format.
• Invalid namespace Meeting Response

If you want to keep using version 9, you can switch the sending protocol from AirSync to SMTP.

On Windows:

Close eM Client. Download and run this configuration file to update the Windows registry.

You can also change it manually if you prefer:

• Run REGEDIT in Windows Start menu
• Navigate to HKEY_CURRENT_USER\Software\eM Client
• Right-click > New > DWORD and name it UseAirSyncSendMail

On macOS:

Close eM Client. Open Terminal and run this command:

defaults write com.emclient.mail.client UseAirSyncSendMail -bool FALSE

After switching to SMTP, open Menu > Accounts (or eM Client > Accounts on macOS) and disable AirSync under Services. This stops the errors, but Outlook calendar and contacts will no longer work. You can use the local calendar and contacts or add these services from another provider.

Gmail enforces strict daily bandwidth limits to protect its infrastructure and prevent abuse. This restriction can happen during intensive syncing, large mailbox downloads, or frequent send/receive actions. If your account exceeds the number of requests allowed for that period of time, Gmail will apply a limitation known as “throttling”. The restriction is only temporary and will be lifted automatically after a day.

You can also try to restrict the amount of data downloaded into eM Client.
Go to Accounts and under the IMAP tab of the affected Google account, disable download for offline use or limit the time period of messages you synchronize to decrease the amount of data downloaded at the same time, at least temporarily. 
You can try increasing the time period over the following days if you need the full message history downloaded locally.

If throttling continues for an extended period of time even with these precautions, there might be additional issues on your email provider's side. In that case, please report this to the Google support team so they can look into it or reconsider these limitations. 

How can you tell if your account is being throttled?

Throttling is usually visible in the IMAP diagnostic logs. A snippet of what it looks like in the logs:

01: A3 OK Success [THROTTLED]

01: A4 NAMESPACE

01: * NAMESPACE (("" "/")) NIL NIL

01: A4 OK Success [THROTTLED]

01: Detected server type: Gmail

01: A5 ENABLE CONDSTORE

01: * ENABLED CONDSTORE

01: A5 OK Success [THROTTLED]

The -ERR NTLM Failure error is usually caused by a mail server configuration issue.

Some mail servers advertise NTLM as a supported authentication method even though NTLM authentication has been disabled. When eM Client attempts to use it, the server rejects the connection and returns this error.

The proper fix is to update the mail server configuration so it no longer advertises NTLM if it is not supported. Please contact your mail server admin or email provider to have this corrected.

If the server cannot be updated, our support team can provide a workaround.
Before contacting us, please enable logging for the affected account under Accounts > Diagnostics, save the changes, restart eM Client, reproduce the issue, and then send us the logs. You can find the log file location under Settings > Advanced. The workaround needs a specific alternate authentication method to be used, so we cannot provide advice without the log.

On some Windows devices with both eM Client and Microsoft Outlook installed, Outlook keeps showing this message:

Either there is no default mail client or the current mail client cannot fulfill the messaging request. Please run Microsoft Outlook and set it as the default mail client.

When you click OK or close it, the error window reappears. It seems to have started after eM Client 11 was installed or updated, but the issue is a bug in specific versions of Outlook/MAPI.

How to fix it

Before you start, shut down both eM Client and Microsoft Outlook.

Option 1: Enable legacy MAPI registration

This fixes the error in most cases. You can apply it with our registry file or by hand. Both have the same result.

Method A: Use our registry file (recommended)

1. Download the fix here: AlwaysUseLegacyMapiRegistration.reg
2. Double-click the downloaded file.
3. If Windows asks whether you want to allow the app to make changes, click Yes.
4. When Registry Editor asks you to confirm adding the information to the registry, click Yes, then OK.
5. Start Outlook and check whether the message still appears.

Method B: Create the registry value manually

1. Press Windows + R, type regedit and press Enter.
2. Go to HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail
3. Create a DWORD (32-bit) value named AlwaysUseLegacyMapiRegistration and set its value to 1.
4. Close Registry Editor, start Outlook and check whether the message still appears.

Option 2: Use the extended registry file (if Option 1 doesn't help)

If the message still appears after Option 1, this file goes a step further. It:

• Sets Microsoft Outlook as the default Simple MAPI mail client, replacing the packaged (MSIX) mail registration.
• Turns on AlwaysUseLegacyMapiRegistration for both 64-bit and 32-bit applications.
• Removes any per-user mail client override, so the system-wide setting above is applied.

1. Download the fix here: DisableEmMapi.reg
2. Double-click the downloaded file.
3. If Windows asks whether you want to allow the app to make changes, click Yes.
4. When Registry Editor asks you to confirm adding the information to the registry, click Yes, then OK.
5. Start Outlook and check whether the message still appears.

Please note
We have observed that Option 1 fixes most cases of this error, but not every single one. If it doesn't help, try Option 2.

If one of the registry fixes worked once but the error comes back after some time, for example, after a Windows or eM Client update, simply run the same file again.
Unfortunately, MSIX installation will reset the registry each time, so if you need to keep using both eM Client and Outlook, you will need to re-run the registry file after every update.

Still seeing the message?
If the error persists after trying Options 1 and 2, please contact our support team at [email protected] and include:

• Your version of eM Client from Help > About
• Your version of Microsoft Outlook (for example, Outlook 2019, 2021, 2024 or Microsoft 365)
• Any add-ins or plug-ins you use in Outlook (for example, calendar or contact sync tools)
• A screenshot of the error message

When you add a Microsoft 365 work or school account to eM Client 11, Microsoft might show the "Need admin approval" dialog without giving you an option to continue. This happens in organizations that don't allow users to approve third-party apps on their own. eM Client 11 connects through Microsoft Graph and needs new permissions, so it must be approved again, even if your organization approved eM Client previously.

To ensure all permissions are added correctly, send this link to your administrator:

https://login.microsoftonline.com/organizations/v2.0/adminconsent?client_id=e9a7fea1-1cc0-4cd9-a31b-9137ca5deedd&redirect_uri=https%3A%2F%2Femclient.com%2Foauth2&state=graph-only&scope=offline_access%20openid%20email%20profile%20https%3A%2F%2Fgraph.microsoft.com%2FUser.Read%20https%3A%2F%2Fgraph.microsoft.com%2FUser.ReadBasic.All%20https%3A%2F%2Fgraph.microsoft.com%2FMailboxSettings.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FMail.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FMail.ReadWrite.Shared%20https%3A%2F%2Fgraph.microsoft.com%2FMail.Send%20https%3A%2F%2Fgraph.microsoft.com%2FMail.Send.Shared%20https%3A%2F%2Fgraph.microsoft.com%2FCalendars.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FCalendars.ReadWrite.Shared%20https%3A%2F%2Fgraph.microsoft.com%2FTasks.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FContacts.ReadWrite%20https%3A%2F%2Fgraph.microsoft.com%2FShortNotes.ReadWrite

The administrator opens the link, signs in with an admin account and clicks "Accept". After that, add your account in eM Client 11 again and it should go through.

Note for administrators:
Please use this link instead of "Grant admin consent" in the Microsoft Entra admin center. The admin center doesn't list all the permissions eM Client 11 needs, so consent granted there may not work.