Moving Mailboxes in a Hybrid Configuration – Part I

In three earlier blog posts I explained how to implement directory synchronization and how to create an Exchange hybrid configuration:

These steps will create a hybrid configuration between your on-premises Exchange 2013 environment an Exchange Online, but to move mailboxes from Exchange on-premises to Exchange online (or vice versa) you need to create an endpoint. This an on-premises Exchange 2013 server (but it can be more) where the Mailbox Replication Service (MRS) is running, used to move mailbox data from one server to another. The process is similar to an on-premises mailbox move where the MRS is responsible.

Create a migration endpoint

To create an endpoint you have to go to the Exchange Admin Center in Office 365 and login as an Office 365 tenant administrator. You can get there via the Microsoft Online Portal, select Admin | Exchange, or navigate directory to the Exchange Admin Center, and login as an Office 365 tenant administrator.

In the Exchange Admin Center dashboard, under Recipients select migration. At this point an empty screen will be shown:


To create a new endpoint, click on the more option (the three dots, next to the refresh button) and select migration endpoints. Click the + icon to start the new migration endpoint wizard. For the migration endpoint type, select Exchange Remote and click Next.


In the next window, enter an email address of an on-premises mailbox. This mailbox will be used to test the new endpoint. Also enter an on-premises administrator account and its password:


Klik Next to continue. The wizard will now run and configure a new endpoint. The wizard will use Autodiscover to find the correct FQDN, but when it fails you have to enter the FQDN of the endpoint manually:


Enter the FQDN and click Next to continue. Give the migration endpoint an acceptable name, and enter the maximum number of concurrent migrations (i.e. move requests) and the maximum number of incremental syncs.


Click new to continue and have the migration endpoint created. When finished the new migration endpoint will show up in the list.


At this point we have created only one endpoint. You can use a (hardware) load balancer to distribute multiple migration endpoints. However, a load balancer will not always distribute incoming requests evenly across available Exchange 2013/2016 servers, so it’s better to have multiple hybrid servers, connected directly to the Internet (using names like, and create multiple endpoints. To make it a bit easier, it is possible to use a wildcard certificate in this scenario.

When you click close the wizard has finished an you’re ready to start moving mailboxen from Exchange on-premises to Exchange Online. This will be subject of my next blog post.

2 thoughts on “Moving Mailboxes in a Hybrid Configuration – Part I”

  1. Does the migration endpoint search for the external domain name ( or the internal domain name (servername.domain.lan or loadbalancerdnsrecord.domain.lan)? And what should the website /ews/mrsproxy.svc respond with? 400 or 200 or ???


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