Someone just brought this to my attention today: Outlook 2016, when it needs to prompt for user credentials to authenticate (if I delete my Exchange keychain entry for example), automatically fills in the user's email address in the "user name" field rather than their username. This will cause authentication to fail for on-prem Exchange if the user simply enters their password. They need to edit the field to be their username.
Has anyone else seen this? I assume this is how O365 authenticates and this is a bug based on that. We'll need to train users to do this themselves when they have a password change or other prompt.
