What process converts a source mailbox to a linked mailbox?

I am using QMM for Active Directory to migrate only users and computers from the source to the target domain. Currently, the users have their mailboxes on the source domain, and my plan is to migrate the users to the target domain.

I'm curious about the stage or process that will convert the user mailbox in the source domain to a linked mailbox, ensuring that plnkgame.com once the user is in the target domain, they will continue to have access to their mailbox. Will ADPW handle this conversion?