I work for an ISP and wear a bunch of different hats but one of them is my "mail server admin hat". I hated our (when I started) Windows-based piece of crap "s

I work for an ISP and wear a bunch of different hats but one of them is my "mail server admin hat". I hated our (when I started) Windows-based piece of crap "solution" we were using and have been migrating all of our users and domains to a "proper" Postfix+Dovecot on FreeBSD mail system. All hosted e-mail lives under /var/vmail on its own ZFS dataset ("filesystem"). I snapshot this dataset (via cron) several times per hour and ship those snapshots off to another machine in a different datacenter for safekeeping. If anything tragic were to happen to the mail server itself, I've got a pristine copy of all my users' mailboxes I can turn to that will be, at most, roughly 15 minutes out of date.