Symptoms/Problems:

After enabling Multifactor-Authentication (MFA) in Office365 for a user, archiving of emails of that user in MailStore Server or MailStore SPE is not possible using a “Single Mailbox" Archiving profile.

•  An error message is returned in MailStore during the archiving process: 
  “An Error has occurred. Authentication failed (EWS).
  Check username and password. If the password is correct, try specifying your UPN Logon (e.g. user@domain.com) or DOMAIN\username in the username field.”

• In addition, the user cannot login to MailStore. An error message is returned by MailStore during the login process: 
  “Mailstore was unable to log in to the server. Maybe your username or password are wrong, or your account is currently disabled.”

Root Cause:

Certain non-browser applications, such as MailStore, do not support “Two-Step Verification”. To get around this issue you need to create an auto-generated app-specific password to use with each non-browser app, which is dedicated to the application it is generated for and separate from your normal password.


Solution:

• Create an application specific password (app password) for the user in Office365.
  
  
• Use the app password as the new password in the MailStore archiving profile.

This URL can help you to create an app password.

Refer to the MailStore online help information located here.

Article-ID: KB20190801-0-EN (Deutsche Version)