Forum Discussion
Cross tenant Migration of user data and emails office 365 to office 365
I am currently working on a cross tenant Migration and the downside of the Migration tool in exchange is that once the email data is moved to the target tenant the source email address is not accessi...
No tools will allow this without performing additional work. You can do one of two things. The first is to set up forwarders in the source tenant to forward mail to users in the target tenant (either on the mailbox or as a transport rule). This option does not allow the migrated users to have a from/reply-to address of that domain though. Be aware that forwarding is disabled in Exchange Online by default so you'll need to allow this.
The other option is to remove the domain from the source tenant, add it to the target tenant and configure mail routing for that domain to go to the target tenant. There is some downtime with this as you need to first remove the domain, then add it to the target tenant, then add the required smtp proxy addresses to your users in the target, then configure mail routing to the target tenant. This can take some time depending on the size of the tenants, and mail will need to be queued somewhere during this period.
If the source domain is not needed after two weeks I'd recommend the former rather than the latter.
The other option is to remove the domain from the source tenant, add it to the target tenant and configure mail routing for that domain to go to the target tenant. There is some downtime with this as you need to first remove the domain, then add it to the target tenant, then add the required smtp proxy addresses to your users in the target, then configure mail routing to the target tenant. This can take some time depending on the size of the tenants, and mail will need to be queued somewhere during this period.
If the source domain is not needed after two weeks I'd recommend the former rather than the latter.