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.