Email domain change and Outlook username

Have you updated the AD User details so that the email address matches the new domain?

Thanks for the reply. Yes, I first did the user (changed the default email address) and expected that Outlook would update automatically (like it does ie when a user moves servers). But Outlook didn't update so I changed the username manually and I am still facing the problem mentioned above.

Did you rebuild the Outlook profile?

No, I don't want to rebuild the profile, I want to update it with the new primary email address/username.

OK, but I believe that a Profile rebuild will clear the error.

Maybe another expert can suggest something else.

Good Luck
Mark/

If you are changing your default SMTP domain you need to do the following...
- ensure that you have registered your MX, A, Autodiscover DNS records with an external DNS provider for the new domain name
- Purchase a SSL SAN cert for your CAS using mail.newdomain.com and autodiscover.newdomain.com for the SAN names, enable all of the services required i.e (iis,smtp,imap,pop)
- in EMC you need to create a new Accepted Domain for newdomain.com (Org Config, Hub Transport)
- you then need to create a new EAP (email address policy) for all of the users that will be aquiring the new SMTP domain
- Make sure that the email address policy for the new domain is the default policy
- Apply the policy to all of the appropriate users
- Ensure that all of your virtual directories are setup accodingly with the new smtp domain mail.newdomain.com, autodiscover.newdomain.com etc

Once you have done the steps above correctly you should not have to do anything on the client end.

Note: if you use cached exchange mode for your users the SMTP domain for the users will not be updated until the next OAB generation cycle has been completed. If you use OWA or exchange online (non cahced mode) you will be able to see the changes immediately.

Will.

First of all, it is not supported to change organization name by Microsoft till now.
If you want to continue to change, I will provide this similar thread for reference.
https://social.technet.microsoft.com/Forums/exchange/en-US/e57c2381-d699-4e20-a492-33278339bf28/company-name-change-how-to-approach-changing-urls-and-san-certs-for-minimal-impact?forum=exchange2010
Good luck.

Hello everyone and thanks for the replies. Unfortunately none of the above answers my questions. The Exchange Server side is configured properly and doesn't have any problems. I can setup a brand new Outlook profile/account on newdomain.com through autodiscover without any problems. My issue is the 200 users out there with existing profiles.

a. Outlook doesn't automatically update the Outlook username with the new domain. Meaning that the Exchange settings in Outlook still look like this:
Is this by design?

b. I went in [Control Panel > Mail > ... > Exchange Account Settings] and manually changed the username from user@olddomain.com to user@newdomain.com. On the surface everything seems to be working fine. However the Outlook Credentials popup looks like this:

So although I have changed the account settings and they properly resolved to the new domain, in the background Outlook still thinks @olddomain.com. I have also confirmed that the account (still) uses the olddomain autodiscover. Is there a way to update Outlook without recreating the profile?

Thanks! :-)

No solution was provided by the experts. Posting the solution for reference.