When you use IMAP to connect to your email account in Microsoft Outlook 2016, authentication fails.
This issue may occur because you have a Unicode character in your password, such as one of the following:
ä ö ü
To work around this issue, use one of the following methods.
Method 1: Change your password
Change your password so it no longer contains any Unicode characters.
Method 2: Use a different protocol than IMAP
You may be able to configure your email account to use POP3 instead of IMAP if your email server supports POP3 connections. The following steps will create a new Outlook profile that's configured to connect by using POP3.