On Wed, 25 May 2016 10:17:19 -0500 (CDT) sha...@shanew.net wrote: > So, for those with more experience, what is the preferred way to run a > backup MX (or two or three, etc.) without losing or breaking the > benefit of spam filtering?
For small installations, I find a backup MX is more trouble than it's worth. So I just don't bother. Seriously, if your Exchange server or whatever is down for more than a couple of hours, you have deeper IT infrastructure problems than can be solved with a backup MX host. For large installations, I run multiple MX hosts that all run as part of the same spam-filtering cluster and which then relay onward to the real mail host. Of course, it's important for the scanners to be aware of all valid recipients on the back-end so they can reject mail to invalid recipients without causing backscatter. Regards, Dianne.
