Error
Microsoft 365 user names should always be specified as email addresses
Description
This error indicates that the specified Microsoft 365 user name is invalid. Microsoft 365 requires users to log in with an email address, not a user name as in "John Doe" or "domain\johndoe".
Resolution
Please review the following information and make the necessary corrections to your case.
- If using administrative credentials for Microsoft 365, check the admin user name specified on your project.
- If not using administrative credentials for Microsoft 365, check the mailbox owner user name specified on the mailbox.
- In all cases, make sure the user name works when logging in at https://login.microsoftonline.com.