After having a little outage due my my ADSL router deciding to take a couple of hours off, I decided I really really really did need to sort out a secondary MX. I have a little Ubuntu server in a rack offsite that I toyed with for a while but never seriously did anything with once I got distracted with other things.
Now of course it is going to be my store-and-forward server for when my home mail server disappears off the big scary Internet. A Store-and-forward server is basically a mail server that relays mail for a certain list of known domains. It will also be prepared to hold mail in the queue for a few days until the primary is back to life.
The best description and config help I found was here. Well worth a look if you want to do this kind of thing yourself for free on old hardware for when that expensive Exchange mail server (or in my case cheap Mercury server) decides it doesn’t want to play any more.
Postfix is currently not being too helpful and I’m going to rip-and-replace it. It should be a simple config but I couldn’t help trying to refine it. Oops. It also doesn’t help that I seem to fallen fould of te “smtp fixup” provided by the over-eager Cisco ASAsitting in front of it.
Another good site for novice Postfix admins is here. It lists a verbose config with lots of good little security-concious snippets.