This script exports users from an OU to a CSV that can be used by other scripts.  I had to move hundreds of users from one domain to another and modify some user properties during the process.  A CSV file allows you to open the file in Excel and edit the fields as needed.  You can take the output of this script and use it to create uses in a new domain with this script.

Get-Mailbox -OrganizationalUnit "User OU" | Export-Csv -f User_Mailboxes.csv

Export details for all mailboxes for user in OU.txt (76.00 bytes)