Handling email domains during an Office 365 Tenant Migration

Office 365 tenant to tenant migrations, where you migrate users and data from one Office 365 subscription to another are becoming more and more common, and because organizations adopt more Office 365 services other than just email, they are also becoming more complex. Often you will need to migrate OneDrive for Business data, SharePoint sites, Office 365 Groups and manage the transition for services like Teams, Yammer, Skype for Business and more.

But that doesn’t mean that the email migration has become easier. Although Microsoft announced at Ignite 2017 that they would in the future improve tenant-to-tenant email migration capabilities, the functionality to do so hasn’t yet arrived. Therefore third-party tools are the order of the day when you need to accomplish this.

One particular issue that you need to be aware of is how to handle moving email domains in Exchange Online during a migration. This is because email domains (or rather Custom Domains, in Office 365 terminology) can only be associated with one Office 365 tenant at one time. This makes it complex if you need to move mailboxes across from one tenant to another and retain email addresses.

To explain this in more detail, I’ve written a long article, split in two parts for Quadrotech, one of the leading software vendors who make Cloud Commander, a tenant to tenant Office 365 migration tool. You can read parts one and two over on their Cogmotive Office 365 blog:

Handling email domains during an Office 365 Tenant Migration Part One

Handling email domains during an Office 365 Tenant Migration Part Two

If you fancy learning a little more about tenant to tenant migrations in general, then on’t despair. I’ve recorded with Jason Wynn a couple of episodes on this very topic on the All About 365 podcast. Episodes 4 talks about this in the context of Microsoft Teams, and on Episode 5 we are joined by Tony Redmond to go for a bit of a deeper dive. Enjoy!