@joseph Yes, all of them since the very first email I ever sent or received (minus spam, of course). I'm doing POP3S to my 24/7 #Linux based homeserver. I can access mail from everywhere using SSH and mutt. Backups via rsync to one or two other Linux boxes or external disks.
@joseph Yes, at the office we all use thunderbird, the data folder is backed up once a week to a backup server