Taking out PST also take out the X500 address of mailboxes and add them back in the new mailboxes on migrated forest..
Jason Crawford
You're going to have to upgrade your 2013 server to 2016. Unless you want to test your upper limit of frustration don't try to migrate using .pst files. Since the mailboxes all live in a separate forest there is no need for legacyExchangeDn / X500 addresses either. The challenge you'll face is password and SID history both of which are accounted for in the ADMT (Active Directory Migration Tool); however, it's not really appropriate in this instance since the AD users and mailboxes are already established in the target. If flipping the migration from 2013 to 2016 isn't an option you'll most likely want to shell out the $9.99 per mailbox for Migration Wiz, otherwise the next best option I can think of is introducing a third forest (similar to a resource forest) to facilitate the unique position you're in. I'm happy to help if you need a hand.
Eprs_Admin
ASKER
Hi Jason,
can you confirm, I have to upgrade the EX2013 ?
Now when I try to move the mailboxes to the new forrest with GUI, I get this error:
Can you explain what your client's requirement?
Maybe we can propose something better.