Exchange owa opens wrong mailbox

Copper Contributor



Yesterday I changed from Forms Based Authentication to Windows Integrated on Exchange owa and ecp. Today a couple of users noted that when they opened webmail they got presented with other users' mailboxes. After a few refreshes they got in to their own mailbox.


As far as I know and can find they should have no permissions to open these other mailboxes.


Obviously I had to revert to FBA and after that everything seems to be fine again. 

Exchange 2019 CU12 Mar23SU on Windows Server 2019

1 Reply

@Joakim Silverdrake 


I understand that after changing from Forms Based Authentication to Windows Integrated on Exchange owa and ecp, user(s) begin to experience sign-in issues like Outlook Web Access Opening the wrong Mailbox.

You confirmed that when you revert back to the Forms Based Authentication, issue stops happening. Can I know the URL user(s) log in to OWA with? Can user(s) try accessing Outlook on the web using the link https://<ServerName>/owa and ensure affected users are using the supported web browsers.

The Supported Web browsers for Outlook on the web in Exchange 2019 are Microsoft Edge, Internet Explorer 11, and the most recent versions of Mozilla Firefox, Google Chrome, and Apple Safari.

Lastly, confirm if issues occur when on the incognito mode browsers as well. Feel free to reach out to me if you need further assistance. Thank you!


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