Trouble setting up and alias to another domain in our tenant

Question

Small Business, Standard license.

2 domains in tenant: Domain1, Domain2.

User JoeBlow@domain1 listed in active users with no alias.

Tried to setup an Alias JoeBlow@domain2 but it said that email already exists.

Did a search for JoeBlow@domain2, no results.

Sent email from my personal email address to ******@domain2.com.

JoeBlow@domain1 received this email.

When he replied it came from ******@domain1.com.

We have done this before with no issues, but not for awhile. Has MS changed something where, if your tenant has 2 domains registered, when you set up an email address in one it automatically creates a second one in the other domain with the same username?

I cannot find any reference anywhere to JowBlow@domain2.

Answer 1

If the test email you sent to ******@domain2.com was received by the account, you likely already have that alias added. But there are some other methods that can be used to ensure that messages are being delivered to the "correct" recipient.

If you are familiar with PowerShell, you can confirm this by running the Get-Mailbox cmdlet, like this:

Get-Mailbox ******@domain2.com | select -ExpandProperty EmailAddresses

and in case the above query returns nothing, you can double check via

Get-Recipient ******@domain2.com

That second cmdlet will return any object within your tenant that might have the alias configured on it.

Another thing you can do is run a message trace and check the detailed information therein, it will tell you how/why the message got to the final recipient. Here's the relevant article: https://learn.microsoft.com/en-us/Exchange/monitoring/trace-an-email-message/message-trace-modern-eac