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.

The best way to ensure all your data and settings are brought over is through Backup and Restore.

Follow these steps:

In the old device:

1.        Create a backup through Menu > Backup (Menu > File > Backup in eM Client 7 and older)
2.        Deactivate your license if you are no longer going to use eM Client on this device in Menu > Help > License (not needed for one-seat licenses, but useful for making sure no licensing problems happen)
3.        Find the .ZIP backup file and move it to your new device
   (by default in ..\Documents\eM Client)

In your new device:

1.        Install eM Client (download it here)
2.        Skip initial setup
3.        Restore from your backup through Menu > File > Restore
4.        Activate your license in Menu > Help > License

If you put the backup file in the new device in the same folder structure as the default (..\Documents\eM Client) the restore will find it right away. Otherwise, you'll need to specify the path where the backup file can be found (in Menu > Settings > General > Backup).

You can also find these steps in our blog here: Transfer Your eM Client Data to a New Device

Free license, as the name implies, can be registered at no cost. This license is meant for personal use and some of its features are limited.
Personal and Business licenses are paid licenses with no feature limits. Find the list of all features on our Pricing page or the License model page. You can decide to buy the license as a subscription or for a one-time fee.

While the Free license allows you to set up a maximum of two accounts in eM Client, it is possible to add an unlimited number of accounts with the Personal or Business license.

Free license can be activated on one device at a time.

The paid licenses also enable you to use eM Client for commercial purposes. Commercial use is any activity that helps you make a profit – the Free license therefore cannot be used in company settings or on personal computers for any kind of work or business correspondence.
The Personal license is intended for home use and for freelancers or sole proprietors.
Personal license cannot be used in companies, schools, non-profit organizations, governments, or any other institutions, even if you are just an employee. In these cases, a Business license is required.

Business and Personal license users also gain access to the dedicated VIP support system. The support options are fully described in the Support overview.

If you’re not sure about the type of license that you need, please get in touch with our sales department at [email protected]

In the eM Client application, go to menu > Help > License.

Click the ‘Activate’ button and insert your activation key (including the hyphens).

If there is no Activate button and this section already seems to include some License information it means there already is a license activated on this computer.
If it's the correct license, you don't need to do anything.

If you wish to activate a different license, simply click ‘Deactivate’ first to remove the current license. The same button will then be replaced by the ‘Activate’ option so you can proceed using the steps above.

The backup options are accessible in Menu > Settings > General > Backup.
You can choose the folder where the backups will be saved and once you check the ‘Enable Backup’ option, you can also select how often you’d like the backup to occur and how many backups you want to keep (you can store up to five different backups at a time).

To change the time of the backup on Windows:

1.        Open up the Windows 'Task Scheduler' tool
2.        Click on the Task Scheduler Library
3.        You will see eM Client Database Backup in the middle window amongst the other tasks – double-click it to open the properties
4.        Go to the ‘Triggers’ tab
5.        Now you can edit the time and day when the backup takes place.

Mac does not have a default system scheduler, so the time needs to be changed either using a 3rd party app that has this functionality, or you can change it in the file ~/Library/LaunchAgents/com.emclient.mail.backup.plist

If you want to change the backup time to the current time, you can do that from inside eM Client:

• In eM Client > Settings > General > Backup uncheck Enable periodic backup
• Click 'Apply'
• Enable periodic backup again
• Hold the Alt (or Option) key and click 'Save & Close' or 'Apply' - this should change the backup time to the exact time you changed the setting.
• Restart launch agent - open terminal and run these two commands: 
• launchctl unload ~/Library/LaunchAgents/com.emclient.mail.backup.plist
• launchctl load ~/Library/LaunchAgents/com.emclient.mail.backup.plist

The default time for the backup on macOS is 10:00 AM.

Don’t worry, a lost activation key is no problem.

Simply enter the email address used for the license registration here and we will send you your activation key immediately.

If you have problems receiving the key, please make sure that you entered your address correctly and also check your Spam folder.

If you’re worried that you cannot retrieve your key because eM Client is in offline mode, please be aware that most email providers in this day have a webmail option, where you can login and get your messages through your internet browser (for example Gmail addresses can be checked in your browser at mail.google.com, Hotmail, MSN, Outlook and other Microsoft accounts can be checked at outlook.live.com, etc.).

Basic eM Client licenses are meant to be used on one computer only, so if you have one eM Client license and are using eM Client on two or more computers, you will be asked to re-activate your eM Client license each time you switch between the computers.

However, we offer significant discounts on multi-license orders so you can purchase all the licenses you may potentially need in bulk. If you have any questions regarding the purchase or would like to talk about the pricing individually, please contact our sales department at [email protected].

The default database location is in the eM Client folder under your user profile in hidden folders AppData\Roaming (the path is usually C:\Users\%username%\AppData\Roaming\eM Client).

To change it, please navigate to Menu > Settings > General > Storage where you can adjust the database folder location.

However, as the disclaimer in the settings warns: when you change the location, your original database will not be transferred. Instead, a new database will be created there on the next startup, unless you move your old database files into the new location.

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.

All official themes are already included inside eM Client. You can view those in Menu > Settings > Appearance > Themes.

In eM Client 8, we introduced a new Theme editor with a direct WYSIWYG mode.

You can find all steps and tips in this article.
For example, if you want to enable wider scrollbars, you can now easily find the setting under Elementary controls > Scrollbars, and check the UseSystemScrollbar option.

Tip: The option to change this is now also available directly in menu > Settings > Appearance > Lists under Scrollbar style.

Don't have the time to design your own theme right now but the official themes don't fit your style?

You can also choose from our user-created Theme gallery.

After creating or downloading your new theme, you still need to Import it in Menu > Settings> Appearance > Themes and then select it from the Theme list to apply it.

LEGACY OPTIONS

Steps to follow for eM Client 7 and older:

1.        Select the theme you want to base your own theme on.
2.        Click the ‘Advanced’ button and select "Save current theme as..." – the theme file will be the saved as a .emtheme file.
3.        Open the .emtheme file in any text editor
4.        Adjust or recreate your theme using the available tags, each item is explained in the comment inside the file
5.        Save your theme file
6.        Go back to Themes settings
7.        Click the Import button and import your new theme
8.        Select it and Apply it
9.        You have successfully changed your eM Client theme! 

Example for direct XML edit:

If you just want to make a small change, for example, enable wider scrollbars, find the relevant line and change the True/False value.

<UseSystemScrollbar description=""Use system scrollbars with no automatic hiding"">False</UseSystemScrollbar>

Colors are saved in HEX codes, there are many sites that provide color pickers and provide you with the code - for example Color-Hex.

Note: User-made themes can also be found on our Forum, just search for 'Theme'.

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.

Yes, you can definitely use a number of startup parameters.

Here is a short overview:

    /dblocation PATH

    This parameter will determine which folder will eM Client load the main database from. If the given folder does not exist, eM Client will create the folder and a new, empty database in it. Without this parameter, eM Client will load the database from the currently set default location.

    /localmutex

   Use this parameter when deploying the application in a Remote Desktop Services or Terminal Services environment where accessing global mutexes (short for „mutual exceptions“ in programming) is forbidden – the application will use local ones instead.

    /mailurl RECIPIENT

    Use this parameter to create a new message with a pre-defined email address compliant with RFC 6068.
Example: MailClient.exe /mailurl "mailto:[email protected]?subject=hello&body=bodytext"

    /open PATH

    With this parameter you can open any .eml, .msg, .vcf, or .ics file in eM Client.

    /newmail

    This parameter will open a window to compose a new mail.

    /newcontact

    This parameter will open a window to create a new contact.

    /newevent

    This parameter will open a window to plan an event.

    /newtask

    This parameter will open a window to create a new task.

    /importsettings PATH [-s] [-p PASS]

    This parameter defines a file which contains eM Client settings and its password, which needs to be used to import the data. It needs to be an .XML file and can contain application settings, account configuration, templates, quicktexts, and rules. PATH is the location of the file. The rest of the parameter options are optional. [-s] stands for "silent" and means that the settings will be imported without opening the UI. [-p PASS] is for inserting the password, if there is one protecting the file.
Example: MailClient.exe /importsettings "c:\Temp\settings.xml" -s -p MyPassword

    /activate

    You can easily activate your eM Client using this parameter and activation key.

    This parameter can also be used without the Activation key, but for activation to be possible in this case eM Client needs to have a LastActivationKey entry in its database with a valid Activation key. Usually, the LastActivationKey value is set using the /importsettings parameter.

    /deactivate

    This parameter will deactivate the license in your device. This can be useful when you have a set number of seats on your license and want to quickly free up the space by deactivating the device you no longer plan to use.

Note: This answer applies only to Windows version.

Read more in the Documentation: Startup Parameters

After you set up your Gmail account you might encounter this error message:

'All Mail' folder disabled

For Gmail and Google Apps accounts, eM Client synchronizes the 'All Mail' folder. It appears that IMAP access for this folder on account '<your email address>' is currently disabled and synchronization will fail.

To fix this, you need to make sure the 'All Mail' folder has 'Show in IMAP' checked in their Gmail settings at https://mail.google.com/mail/u/0/#settings/labels.

Simply follow the directions from the error message and enable All Mail label to be shown in IMAP.

NOTE: The 'All Mail' folder is a vital part of your Gmail account - it stores all the messages in your account (with the exception of Trash and Spam folders - these are separate).
Synchronizing this folder will not create any duplicates of your messages, because eM Client supports this specific Gmail structure and each message is stored only once in the All Mail folder and all the other folders (Inbox, Sent, Drafts, ...) are just Labels - special search folders which will show the messages from All Mail folder with the matching Label. Kind of like Tags in eM Client.

This actually allows for the synchronization to be faster and the data to take up less space on your device than if the Labels were converted into real folders.

eM Client supports two specific kinds of Archiving features:

• Local automatic archiving inside the eM Client program and
• Server-side archiving.

Automatic Archiving

eM Client archiving can be found in Menu > Settings > Mail > Automatic Archiving.

The way eM Client archiving works is that the program will create a special set of local folders called 'Archive'. Archive folders will be shown below all your other account folders and Archived messages will be only available in your device. If you will choose to archive messages from a synchronized account (set up with IMAP or EWS protocols) the messages will be removed from the server as well, so you will no longer be able to access them using webmail.

To make the automatic archiving actually work you need to enable it, set how often the Archiving should happen (Archive every X days), set how old the messages should be (Archive messages older than X days) and most importantly, select which accounts/folders you want to perform the Archiving on (Account Preferences).

Click the ‘Archiving Scope’ field for each Account to select which folders should be included.

You can also perform the archiving manually by clicking the 'Perform Archiving' button. This function can be used even without enabling the Automatic archiving in the top checkmark (Enable Automatic Archiving).

Server-side Archiving

For IMAP and EWS accounts the Archive feature will move messages into a single folder called 'Archive', which will be among the other special folders like Inbox, Sent, Drafts, etc.
You can select a message (messages) and use the Archive option via right-click, toolbar button or the default shortcut Ctrl+Shift+A.

The shortcut can be changed in Menu > Settings > General > Shortcuts.

An exception to this is the Gmail Archive. This is a specific function which removes the 'Inbox' label from a message in Inbox, leaving the message accessible in the 'All Mail' folder. You can read about Gmail's native archiving and what it means on Google support. 

Read more in the Documentation: Automatic Archiving

eM Client is able to show avatars for your contacts and can also download avatars from external sources like domain icons and gravatar. But how do you change your own avatar?

This cannot be done directly via eM Client yet, but there are ways to get your avatar updated and connect an image with your email account everywhere.

The easiest way to change your email avatar is via Gravatar - https://gravatar.com/
Just create an account with your email address and upload an image.
eM Client will be able to load this image for your email account.

If you own your domain/have a website on the domain you can set up a favicon.
You can read about favicon setup here - https://www.w3.org/2005/10/howto-favicon

Another tool that you might find useful is a favicon generator, to create different sizes of your image - https://www.websiteplanet.com/webtools/favicon-generator

IMPORTANT: Please note that since eM Client updates the downloaded avatars every 30 days, the avatar changes won’t be immediately visible.

However, you can force eM Client to re-download new images by disabling and re-enabling the download of images from external sources, which will clear the image cache:

1.        Go to Menu > Settings > Contacts > General
2.        Disable the option ‘Download avatars from external sources’ and click ‘Apply’
3.        Then enable the option ‘Download avatars from external sources’ again and click ‘Ok’
4.        Your new image will show up now

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.

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.

You can set up and manage some of the rules directly on the server for Exchange, Gmail and IceWarp accounts.

Next to the 'New rule' button in the Rule window toolbar you can now select from Local rules and your accounts' specific server rules.

When the rules are on the server instead of just in eM Client they will be applied to new messages, even when eM Client isn't running. And if you use eM Client on numerous devices, you don't need to set up or copy the rule to each device separately.

In general, the system requirements will be dependent on the current version of .NET used in eM Client. At this time, it is .NET 10.

Windows

• Windows 10 or higher - systems with up-to-date security from Microsoft are recommended, but with some tweaks (like manually enabling TLS 1.2 Win 7) eM Client can still be used on older systems, it is not blocked from our side, but we cannot guarantee it
• 350 MB of free space for installation.
  • You will need additional space for data, which can be stored on a different drive if needed! Since eM Client has no limit on the number of emails/data stored in its database the only limitation is the capacity of the hard drive installed in your PC. Shared folders or network drives are not recommended due to potential database conflicts.
• Minimum of 2 GB of RAM and 1.6 GHz CPU
• Recommended for memory and processor - the more GB and GHz you have, the better :)

Terminal servers

eM Client can, of course, be used in a Terminal Server environment as well. Windows Server 2012 and newer Windows server versions are supported.

Mac OS

We officially support only the last three macOS versions.

There are two different ways to deploy eM Client and activate the license automatically:

1.        Deployment via Command Prompt

If the goal is to simply install eM Client and load the license, use the following command in Command Prompt: MailClient.exe /activate {insert activation key here}

Similarly, you can easily deactivate eM Client license by using: MailClient.exe /deactivate

2.        Automatic deployment

If a bit more complex setup is required, you can use our "Automatic deployment process" which allows you to push various sets of settings along with the license key too. Find more detailed instructions here. 

Read more in our blogs: eM Client Server Settings & Advanced Startup

Sharing in eM Client is done via Delegation for Exchange (EWS) accounts.

You can find the Delegation setting via the Menu>Accounts section in the Exchange Web Services tab of the given account or via right-click on the specific account in the folder list.

• In the Delegation window or section click the Show... button next to "Accounts you can access:"
• The "Delegated accounts" open will open.
• Click the Add button on the Delegated accounts window.
• The "Select users or groups" window will open.
• To add the delegated account you should have access to, enter it under "Enter the name of users or group:". E.g., [email protected]. Then click the Search button.
• That user will be displayed under "Group or user names". Click on the proper account name and click the Ok button.
• Click the Ok button on the Delegated accounts window as well and close/save the original Delegation window.

If the shared folders do not appear right away, try closing and re-opening the eM Client app.

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. 

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

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.

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.

No, you currently do not need a license to use eM Client for Android and iOS.

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.

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 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.