How can i Backup the IMAP Directorys ? rsync from server old to server new (would i do)
to be sure not to loose any mail:
1) stop the services on server old
2) rsync to new server
3) forward everything with rinetd from server old to server new
4) start the services on server new
don´t miss to change all dns settings for the domains to point to the new server(may use a short TTL for faster propagation)