How to handle domains during a Tenant migration

It’s now already some years I am supporting companies with their journey to the cloud. Having read the Microsoft announcment about their plans to build two new Datacenters offering Microsoft Online Services in Geneva and Zurich, I am pretty sure that Engineers like me still will have enough to do for the coming years.

So far I recognise that some oft he companies are now considering to migrate their existing Microsoft Tenant to a new one. Possible motivations for this behaivor could be the fact that Microsoft announced «Multi-Geo», or other reasons like selling parts of the companies such as subsidaires.
There is a fact to consider for those companies which are moving from an existing to another Microsoft tenant. At the moment, we cannot change the region of an existing tenant. This means, microsoft has region groups for the tenants. Moving a tenant from a region to another is just not possible. An overview about these groups can be found HERE.

However, I see this bringing a new chalenge in the near future. Let’s call it a «tenant-to-tenant-migration». If you’re planning to move an existing tenant to a new one, there are several things you may have to consider before doing it. One oft he most critical topics is how to deal with your domain (e.g. contoso.com) in the migration. This topic definitely is in a relation tot he mailflow. Ideally, a migration has no (or very short) service-downtime without any data-loss.
During the last Ignite (2017), Microsoft announced to improve the functionalities related to mail migration for the tenant-to-tenant-migration scenario. So at the moment we still have to wait for this to happen. But organisations usually won’t wait. So at the moment, the only way to deal with this topic is with third-party-tools.

This was about the mailflow. Let’s go to the other topic I mentioned above… the domain handling in Exchange online during a tenant-to-tenant migration. The domain used fort he Mail Service in Office 365 can only be active at one Microsoft Tenant at the time. This requires some creativity if you need to move mailboxes from your existing tenant to your new tenant without having any downtimes.
So basically, the topic about «tenant-to-tenant migrations» is huge and in my opinion it’s crucial to understand it and go with it! Steve Goodman wrote a huge article about this topic for the Tech-Blog «Quadrotech». I can highly recommend you to read it.

Here are the links to both parts oft he Article:
Handling email domains during an O365 Tenant migration | PART 1
Handling email domains during an O365 Tenant migration | PART 2

Steve and Jay also have podcasted about tenant-to-tenant migrations. You can find the Podcast under the following picture below:

 

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