Transferring a domain from one office portal to another

Question

We have two domains under one Microsoft office portal with users, email, and office license assigned to both domains. Now we want to split the two domains into their own separate office portals. So I created another office portal account and want to transfer one of the domains to it. In order to add the domain into the new account I have to remove it from the other account. Which means while I'm doing the transfers there will be a downtime when no one will have access to emails. Is there a better way of transferring the domains from one MS portal to another preserving all users and license? After all they're both MS office portals.

Thanks a bunch.

Answer 1

As far as "moving" the domain - you are correct that is the only way to do it. If you are not using another device to store and forward messages, you may also generate some NDR's if messages are received prior to getting domain and users over to new portal.

Microsoft has an article posted on tenant to tenant moves - search for "How to migrate mailboxes from one Office 365 tenant to another" the current link is: https://support.office.com/en-us/article/How-to-migrate-mailboxes-from-one-Office-365-tenant-to-another-65af7d77-3e79-44d4-9173-04fd991358b7