Hi Support, We have a AD and exchange 2013 in abc.com and planned to migrate user mailbox to new domain xyz.com. We setup new AD and exchange 2019 in xyz.com, and also setup the ADMT server to migrate AD object from abc.com to xyz.com. The question is abc.com user account’s primary email address is using xyz.com already (not abc.com), so both user email address in abc.com and xyz.com will be xyz.com. How to configure the connector and exchange server so the email flow can work normally in abc.com and xyz.com coexistence environment Thanks Best Regards Chong

Hi @Chong , Here is what I thought: The Exchange 2013, you use the email address policy to change the mailbox address from abc.com to xyz.com. While the server fqdn was still Https://ex2013.abc.com and all connectors and records were using it. The Exchange 2019, it's defaultly set to use xyz.com as the mailbox address suffix. The fqdn should be Https://ex2019.xyz.com. And my questions: As you said, you have migrated the AD object from abc.com to xyz.com, have you migrated the mailboxes, or only the AD objects? Two cases: If you only migrated the AD objects, then the Exchange should be a fresh server with no mailboxes and other settings. If you have migrated the mailboxes from 2013 to 2019, then you could set the mail flow to use 2019 server and abandon 2013. Another question is what do you mean of "so the email flow can work normally in abc.com and xyz.com coexistence environment"? AFAIK the two cross-forest servers are not able to work together. And for your case, as the mailboxes in abc.com is using xyz.com as it's email address( added as accepted domain I guess), then you shouldn't use it again in 2019 for internet email flow. I think the best idea should be a full migration and after that you can configure the mail flow settings. And also, please provide more details if I didn't understand your questions correctly:) Have a nice day! Best regards, Lou If the response is helpful, please click " Accept Answer " and upvote it. Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Exchange Cross-forest migration when source and target domain use same email address

Accepted answer

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-01T02:56:51.68+00:00
Hi @Chong ,

Here is what I thought:
The Exchange 2013, you use the email address policy to change the mailbox address from abc.com to xyz.com. While the server fqdn was still Https://ex2013.abc.com and all connectors and records were using it.

The Exchange 2019, it's defaultly set to use xyz.com as the mailbox address suffix. The fqdn should be Https://ex2019.xyz.com.

And my questions:
As you said, you have migrated the AD object from abc.com to xyz.com, have you migrated the mailboxes, or only the AD objects?
Two cases:

If you only migrated the AD objects, then the Exchange should be a fresh server with no mailboxes and other settings.

If you have migrated the mailboxes from 2013 to 2019, then you could set the mail flow to use 2019 server and abandon 2013.

Another question is what do you mean of "so the email flow can work normally in abc.com and xyz.com coexistence environment"? AFAIK the two cross-forest servers are not able to work together. And for your case, as the mailboxes in abc.com is using xyz.com as it's email address( added as accepted domain I guess), then you shouldn't use it again in 2019 for internet email flow.

I think the best idea should be a full migration and after that you can configure the mail flow settings. And also, please provide more details if I didn't understand your questions correctly:)

Have a nice day!

Best regards,
Lou

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.
Please sign in to rate this answer.
Chong 846 Reputation points

2021-10-01T06:03:04.727+00:00

Hi @Xzsssss ,

Thanks for your reply.

Yes. We will perform the domain migration from abc.com to xyz.com. So both user account and the mailbox will migration to the xyz.com domain. User and other AD object will migrated by ADMT, and mailbox will cross-forest migration

My meaning is: As both domain user email address is xyz.com, we need to make sure all user can send and receive internal and external email, no matter they locate in abc.com, or migrated to xyz.com. (It should use xyz.com in new domain as this is business requirement)

I think both exchange 2013 and 2019 should configure xyz.com to “internal relay” in accepted domain.

For the connector, if the email address is different, we can just configure the target address route to target exchange server. But as they are same email address, I don’t know can they route between 2 domain (the MX record can point to either 2013 and 2019)

Thanks

Best Regards
Chong

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-04T09:40:46.74+00:00

Hi @Chong ,

Thanks for the details, that lets me know more about your questions.

Yes you could configure the xyz.com as the internal relay domain and create a send connector for it.

See this post: https://practical365.com/how-to-share-an-email-domain-between-two-mail-systems/
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

And remember to disable recipient lookup by Set-AcceptedDomain XXX -AddressBookEnabled $False.
https://learn.microsoft.com/en-us/exchange/mail-flow/accepted-domains/accepted-domains?view=exchserver-2019#recipient-lookup-in-accepted-domains

Again, kindly suggest you to consider a full migration while not use the above methods. Only when you want to keep both server running:)

Best regards,
Lou

Chong 846 Reputation points

2021-10-04T09:57:37.743+00:00

Hi @Xzsssss ,

Thanks for the information again.

BTW, what is full migration? Can you explain more?
As I said, we will perform the domain migration by ADMT. I will migrate all user/groups/contact/etc from abc.com to xyz.com. Since the ADMT cannot migrate mailbox so we planned to perform the cross-forest mailbox migration.
i
Thanks

Best Regards
Chong

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-06T06:45:34.67+00:00

Hi @Chong ,

Glad to be helpful:)

It means a whole server migration, including the recipients and other items. Well generally speaking, it is to say that the mail flow could be performed by Exchange 2019 alone. And you could decommission Exchange 2013 whenever you want.

I think for your case, you could first use Moverequest to move mailboxes and then use ADMT to migrate the other users in AD without mailboxes.
https://learn.microsoft.com/en-us/exchange/architecture/mailbox-servers/prep-mailboxes-for-cross-forest-moves?view=exchserver-2019

Best regards,
Lou

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-11T09:29:35.507+00:00

Hello @Chong ,

Do the suggestions above help? If the issue has been resolved, please click “Accept as answer” to mark the helpful reply as an answer, this will make answer searching in the forum easier and be beneficial to other community members as well.

If you are still stuck in this issue, please feel free to post your questions.

Regards,
Lou

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Chong 846 Reputation points

2021-10-11T09:39:04.203+00:00

Hi @Xzsssss ,

I still stuck on the migration as the source domain using "mail.xyz.com" for EWS and "autodiscover.xyz.com" for autodiscover, but the target domain also need to use "mail.xyz.com" and "autodiscover.xyz.com".

So the target domain cannot create the migration point to move mailbox.

Best Regards
Chong

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-15T08:22:17.237+00:00

Hi @Chong ,

You could make the DNS records onto Exchange 2019 and use internal relay to proxy connections to 2013.

Best regards,
Lou

Chong 846 Reputation points

2021-10-15T08:30:50.117+00:00

Hi @Xzsssss ,

I know the ex2019 server can proxy CAS connection to ex2013 when exchange migration in same domain.

But it also work in cross-forest domain? That's ex2019 in xyz.com also can proxy connection to abc.com ex2013? Do the internal URL set to "$null"?

Best Regards
Chong

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-15T08:46:19.713+00:00

Hi @Chong ,

I searched the official document and yes the Internal relay can be used for different forest organizations.
See this topic: https://learn.microsoft.com/en-us/exchange/mail-flow/accepted-domains/accepted-domains?view=exchserver-2019#relay-domains

But I have to say that I never used cross-forest domains with the same address, it's all on paper. And what internal URL?

I think you should create the internal accepted domain and then the send connector for internal relay.

For more you could check this doc: https://learn.microsoft.com/en-us/exchange/mail-flow/connectors/outbound-smart-host-routing?view=exchserver-2019

Best regards,
Lou

Chong 846 Reputation points

2021-10-15T09:05:32.997+00:00

Hi @Xzsssss ,

I tried to configure the accept domain to internal relay and email seems can send and receive on both exchange server already.

But I am stuck on the URL used for the EWS and autodiscover services which for mailbox migration

Best Regards
Chong

Xzsssss 8,861 Reputation points Microsoft Vendor

2021-10-18T07:43:45.473+00:00

Hi @Chong ,

You mean the Virtual Directory URL?
I think it should be xyz.com for both internal and external( EMS and Autodiscover):
https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tasks/configure-mail-flow-and-client-access?view=exchserver-2019#how-do-you-know-this-step-worked

https://learn.microsoft.com/en-us/powershell/module/exchange/set-autodiscovervirtualdirectory?view=exchange-ps

Best regards,
Lou

Chong 846 Reputation points

2021-10-18T09:12:47.12+00:00

Hi @Xzsssss ,

Yes. I mean the virtual directory URL.

The abc.com ex2013 configured all URL to "mail.xyz.com and autodiscover.xyz.com" already. Since the new xyz.com ex2019 also need to configure all URL to "mail.xyz.com and autodiscover.xyz.com", the URL of both ex2013 and 2019 will be the same.

When setup client, I think we can handle this by change the DNS server in NIC.

However, when I create the migration endpoint for the mailbox migration. The ex2019 cannot contact to ex2013 because the autodiscover and EWS point to ex2019 itself in xyz.com internal DNS.

Thanks and Best Regards
Chong
Sign in to comment

Exchange Cross-forest migration when source and target domain use same email address

0 additional answers