Hello, ipf. Actually, your problem can be caused by the Unicode characters in your password. I recommend changing your password or as an alternative - trying another protocol than IMAP.

If your email server supports POP3 connections that can also be a solution. https://support.microsoft.com/en-us/topic/authentication-fails-when-you-use-an-imap-server-in-outlook-2016-16273eaf-ec20-83f0-f25c-4277c722d42f you can find more information on how to change it.

If you need more insights on MO365, please, use this link https colon slash slash www dot nakivo dot com slash microsoft-office-365-backup.

The third possible solution is using the 2013 version of Outlook instead of the 2016 one. In the 2013 version, this issue never happens.