When changing UPN.

[Hans_from_Copaco]

We have changed the name of our company. Now we have changed the UPN from user@domainA.com to user@domainB.com.  Most users logon with the new UPN, start outlook, and then see that the name of their mailbox has changed to user@domainB.com.  But for some users that is not, so they keep the org nam as user@domainA.com.  Sending emails goes in both situations with the nu primary email address, so this works fine.

Any idea why this happens?

[#2]

Why. Not sure. But it’s a local profile issue in Outlook. You can redo the outlook profile and it’ll update. Wondering if those with it working are using online only profiles? I didn’t spend a ton of time on it but I know it’s related to that.

[#3]

@Hans_from_Copaco This can be down to a number of factors, but mainly the profile element or even the default mail address settings have been overridden as well within Exchange. 

To test the theory, get a user to send an email from OWA and from their device, this would test if it is a mail profile issue.   If that's not the case, check the mailbox addressbook policy and make sure its not been overridden.