Move Centos / Dovecot email to Google Apps Account
I need to help a friend who is in way over his head. He had a CentOS server that was configured with Dovecot for email that was damaged in an office fire. He is trying to move his email accounts to their new Google Apps account so local damage doesn't cause issues in the future. I have never done this particular move before. What do I need to tell him to do? He has his backup drive and it's connected to a new spin up of Centos 7. Dovecot is installed along with Postfix but he has not configured them yet as I've told him to wait until I talk to the Experts.
Is there an easy way to simply grab the email structure and messages from his user backups and load them into their Google Apps account or does he need to reconfigure this temporary server he has running before we can move the data?