I work for an ISP and wear a bunch of different hats but one of them is my &quot;mail server admin hat&quot;.  I hated our (when I started) Windows-based piece of crap &quot;solution&quot; we were using and have been migrating all of our users and domains to a &quot;proper&quot; Postfix+Dovecot on FreeBSD mail system.<p>All hosted e-mail lives under <i>&#x2F;var&#x2F;vmail</i> on its own ZFS dataset (&quot;filesystem&quot;).  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I&#x27;ve got a pristine copy of all my users&#x27; mailboxes I can turn to that will be, at most, roughly 15 minutes out of date.