User with two emails

Question

We're in a hybrid environment. On-prem exchange and 365. We have an on-prem AD and an Azure AD sync. We have two main email domains for internal users (we'll call them @domainA.org and @domainB,org).

A couple weeks ago, we were cleaning up A records in our external DNS host. We had one called email.domainA.org that we got rid of. Thinking was, no one externally was using that. Turns out we were wrong (not my call or action, just CMA on this) and the 365/on-prem connector was still using it. So, when I'd create a new user in AD, then run an Azure-AD sync, it would create the mailbox on 365, but then it was unable to create it back to our on-prem exchange. Fine. I figure out how to reprovision those few new accounts, run a couple PS scripts and now they exist in both places. Also, we put the A record for that DNS entry back in place. It's all good.

For the @domainA.org people.

I have one @domainB.org user who I can't figure out. I went through the same process, but they reported that every email they send is ******@domainA.org, not B. So I go through all the locations and yup, I messed up. So I go about trying to fix it. I make the change in AD, then run the AzureAD delta sync. That changes in 365, but not on prem. Also, on-prem shows primary SMTP is domainA and lowercase (alias) smtp is domainB. But it won't let me switch it, and I can't change the Reply to address, it's not available. And I can't delete the primary SMTP because there's the process that pulls from AD (email field) and it can't go away.

So I go back to AD and into the Attributes and remove the SMTP: domainA and replace it with domainB. Now it looks good on all the back end locations.

However, when the user emails someone and you open that user's details, on the Outlook client, the domainA is still the primary. OWA shows both emails, but will default to emailing the domainA. If I email that user directly, it goes to them fine, and if they reply, it shows both domains again.

So, it's a local outlook profile, I think. So I go into the users machine, delete the profile, open outlook and recreate it. Send new email, both @domainA and B are showing up still. I ran a get-mailbox -identity "User Name" | Format-list and couldn't find any indication of a domainA in there. Just domainB.org and the Domain.onmicrosoft.com everyone else has.

So I'm at a loss as to where this domainA is still being pulled from for this user.

Answer 1

Hello Ben,

Based on your description above, you have already changed the user's Primary SMTP with domain B, however when the user send emails, the recipient still can see the domain A in the user details. And my understanding is this user's mailbox is on Exchange Online, please clarify if I misunderstand your scenario, thanks.

If so, as far as I know the main possible reason is your tenant global address list (GAL) not updated after you changed the user's SMTP to domain B, however the GAL still showing the user with domain A. Generally the GAL would updated every 24 hours, and if you just make a change to user email address, it may take some more time to be updated through the whole tenant GAL. In this time, please first check if the user's email address is updated in the GAL, open any other user's Outlook Client > address book > select Global Address list (not the offline this round) and find that user to open its details then see if the email addresses are updated as expected.

If the GAL has been updated as expected, this time double check the Offline address book and it could be not updated, and you could try to delete the old offline address book from C:\Users\xxxxx\AppData\Local\Microsoft\Outlook\Offline Address Books and then re-download it from GAL. Offline address books in Exchange Online.

On another hand, if the issue persists after 24 hours, I'd like to collect

1. the details of Get-Mailbox xxxx( the user) | FL
2. If the user mailbox is Exchange Online?
3. If you could find the domain A for that user from Outlook Web App (online)?

Best Regards,

Oliver

Answer 2

Hello Ben,

Please feel free to let me know if you got any further updates, thanks.

Best Regards,

Oliver