Outlook 2019 sometimes failing to add an Exchange account

Just had a problem today where I was unable to setup a particular Exchange mailbox in Outlook 2019, running on Windows 10 Pro.  It only occurred with this particular mailbox as I was able to setup a different Exchange mailbox without issue.  Other computers running Outlook 2016 were connected to the mailbox in question without any issues and OWA login worked fine as well.  It would prompt for a password but never get any further.

Turns out it was a problem with autodiscover that can be resolved by making a small entry to the registry as follows:

1/ With MS Office closed, open the registry (run regedit for example) and navigate to the following path:


2/ Add a new DWORD value named: ExcludeExplicitO365Endpoint and set its Data value to 1, as shown in the image below:

3/ Close the registry and try to add the mailbox again.  This time the autodiscover should work properly and allow you to setup the mailbox.

I believe this will likely be fixed soon but this should hopefully help others out before such time.

* Note to admins: Please mark this as the answer.

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Question Info

Last updated June 8, 2021 Views 6,541 Applies to: