MX backup with Courier-MTA

After having had to take down hedwig a fair few hours over the last week (if you didn’t know, Debian has made a new stable release, and amazingly there’s no pigs flying!) while it under went some fairly heavy software updates. During this time Courier, the MTA we use was back logged with a fair number of E-Mails. Of course some 99.9% of them were just spam, but it make me realise just how much load hedwig is under.

To give you some idea, Apache reports a total of 24884 hits for Feb, 22671 for March and 8998 for April (and we’re not even half way through the month yet!). At peak times we’re getting some 300 hits an hour (which works out at around 5 hits a minute, which while not sounding a lot, remember that this is an average over an entire hour, it’s quite likely those 300 hits are over a period of around 10-15 minutes, making a hit ever 5 seconds.) One of our user’s spam folder currently contains 362 messages. The oldest one being just 3 weeks old, that makes over 100 spams a day, for that one user alone! And that’s only the ones that are detected! This particular user claims to be putting some 20-30 a day in manually himself. I know these statistics aren’t anything like Google or Microsoft’s, but for an ADSL hosted, off the shelf and recycled hardware that’s being maintained by someone who’s never done this kind of thing before, not to mention that SpamAssassin and ClamAV eat RAM like horses with sugar cubes and the way that just about everything seems to connect to MySQL, well I have to say I think things are holding up incredibly well…

So back to my original reason for posting. I’ve started to realise over the last few days that more and more people are becoming reliant on our servers. Everything from the heating, lights and access control to E-Mail, websites, file services and DNS is being hosted from a handful of Unix machines hidden away in a secured cupboard in a building in a village where the ADSL connection can come and go as readily as my dog will eat his dinner and where power outages are as common as crashes on the M11. While everything is backed by several (heavy, and I do mean HEAVY) UPSes, something as simple as me tripping over a network cable can result in undelivered E-Mails (which has happened on more than one occasion), and the increase in reliance on these systems means an increase of responsibility for me. At present only 4 users are relying on the E-Mail server, but this is set to increase in the upcoming months (by a factor of 3 or 4.) It’s only this one service that’s crucial enough to warrant my loosing some sleep at night (as sad as that is, it does.) At present, if the Internet, power or user stupidity goes badly wrong for any substantial length of time, people loose out. And worse still; I loose out.

So the solution is fairly simple. Configure a backup E-Mail server! The only problem is, where? At present the only other server I have access too is located at our home, also in the same village, also on the same BT exchange, also subject to the same regularity of power outages as mentioned. But never mind, it’s better than nothing, and at the very least it’ll prevent E-Mail loss when I accidently pull the wrong cable out 😉

I’ll post follow-ups to this blog as I progress with this adventure. Skimming over the Courier-MTA FAQ it would appear quite simple to configure it as a backup MX. Whether this proves true or not I’m yet to discover.

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