Export and restore emails

Go to

https://imapsync.lamiral.info/X/

SSH into old server

Run this from the root directory /usr/local/psa/admin/sbin/mail_auth_view

Recreate the emails on the new server with the same passwords (if you can, otherwise any password will work)

Then in imap sync put the old credentials in the left, new credentials in the right and click Sync and it should migrate them to the new server