When you try to connect to the Exchange Online mailbox, your provider’s Active Directory Federation Services (AD FS) authentication dialog box is displayed, and you enter your credentials. However, you're repeatedly prompted for your credentials after you've already entered them.
- Your email address differs from your user principal name (UPN).
- You entered your email address in the User name field of the Accounts dialog box in Outlook 2016 for Mac.
Article ID: 3156719 - Last Review: May 12, 2016 - Revision: 1