Restore a mailbox from backup

To restore a users mailbox simply copy the files into place, for example lets say you want to restore the user bob@xyz.com

First find the users path:

tellmail path bob@xyz.com
/var/spool/mailbox/xyz.com/aa/bb/bob.com

cp -r /backup/bob.com /var/spool/mailbox/xyz.com/aa/bb/bob.com
chown mail:mai -R /var/spool/mailbox/xyz.com/aa/bb/bob.com

Or if you wish to restore a specific mailbox, usually you would restore it to a new foldername

cp -r /backup/bob.com/mdir/foldername /var/spool/mailbox/xyz.com/aa/bb/bob.com/mdir/restored_foldername
chown mail:mai -R /var/spool/mailbox/xyz.com/aa/bb/bob.com/mdir/restored_foldername