USING ADMT for cross-forest mailbox migration

Brass Contributor

We're going to use ADMT for cross-forest migration of a selected group of users with their mailboxes and wondering which path is best suitable for the task.

We already set up the new domain and the trust relationship.

We tested a normal user migration, without considering mailboxes at all, just to validate the environment and it worked fine.

Now we're at the point to correctly plan for real user/group migration with their mailboxes.

Given that the new exchange server is in place and configured I'm looking for guidelines to perform the migration.

Particularly i'd like to know if the user and its mailbox have to be migrated at the same time or if we can migrate all the users before and then, at a second stage, we can merge them with a "mailbox" migration



1 Reply


ADMT is best tool to migrate the resources between inter-forest or intra-forest. I almost used it for 3 large enterprises with Exchange 2010 to 2016 migration with legacy to latest version of AD.

There are few consideration need to keep in mind for this migration.

1: User migration should not be Cutover Migration it should be Cloned-Staged Migration with required Exchange attributes.

2: Security and Distribution groups migration should be Cloned to avoid Exchange mail flow interruption due members removed during migration.

3: Mailbox and User migration can not be done at same time it will cause big issue with Organizational sharing (Free/Busy), Group membership lost, Mail flow interruption and so on.

There are lot more consideration cant explain everything on one post. but you may ask further if needed help.



Infrastructure consultant.