Cross forest AD migration by retaining same exchange 2016 domain (email address)

[jaleef]

I have a scenario where I have to migrate AD forest with an exchange server. However the exchange server SMTP address should not be changed and same email address needs to be retained for all users. 

I have setup cross forest migration for users and computers with ADMT. Exchange mailflow is also configured and working between source and target exchange (i created a custom accepted domain for source and target and set external email address). However I have a doubt how the Autodiscover works especially for the external users (mobile devices and not domain joined devices).

Can anyone advise how to configure auto-discovery for internal and external users in this scenario? 

Example:

Source AD Forest : abc.com

Source email domain : abc.com

Target AD FOREST: xyz.com

Target email domain: abc.com

[#2]

Jaleef, I'm now in the same position as you were, did you ever find a solution to your question?

[#3]

Computers on the internal network and joined to the domain will use use the domain SCP record to get the autodiscover details, so you can customise that depending on the domain the computer is joined to.
For computer not on the internal network, I've not tested before, but if you've set the targetaddress attribute on a mailbox you've already performed a migration on, I believe autodiscover will be redirected to that target DNS name. You'll need to publish an autodicover record for the target DNS name and make sure it point to the target Exchange environment. If that doesn't work, you may need to hardcode the autodiscover settings by deploying an xml file via GPO

[#4]

That's interesting. I'll give that a look and see what happens.