Having had my awareness of backscatter increased by this list (thanks everyone) I'm looking to improve the behaviour of our mail servers (and we've already taken a number of steps). Unfortunately I think our setup makes this pretty impossible without using a fairly unwieldy setup, but ideas welcome.
Two mail servers on Barracuda spam filter and one postfix, Barracuda being the primary MX. Under the existing setup the postfix (secondary MX) doesn't deliver mail internally, it passes it on to the Barracuda. The idea being that should the Barracuda fail we can allow temporary internal delivery from this server but for 99% of the time manage all mail via a single interface. The postfix box does run recipient checks on incoming mail but that's it. The problem I see is that once the Barracuda bounces a mail forwarded by postfix with an SPF failure or RBL block we generate backscatter because Barracuda tells postfix that it's not taking that mail and postfix then sends a bounce notification. We could resolve this by allowing the postfix box to deliver internally, but at that point we now need to check two servers for rejected e-mails, maintain two white lists, two spam scoring databases etc. I assume this is more graceful with multiple postfix boxes, but with two differing systems the potential for human error to cause problems is too great, plus it doubles the administrative effort required. At this point I'm left thinking that trying to use these two systems alongside each other is doomed to either backscatter or administrative nightmare, but I thought I'd put it out there in case there's some good way to have them work together. Otherwise it's something for me to raise when the Barracuda is up for renewal. Thanks all. Paul Cocker TNT Post is the trading name for TNT Post UK Ltd (company number: 04417047), TNT Post (Doordrop Media) Ltd (00613278), TNT Post Scotland Ltd (05695897), TNT Post North Ltd (05701709), TNT Post South West Ltd (05983401), TNT Post Midlands Limited (6458167)and TNT Post London Limited (6493826). Emma's Diary and Lifecycle are trading names for Lifecycle Marketing (Mother and Baby) Ltd (02556692). All companies are registered in England and Wales; registered address: 1 Globeside Business Park, Fieldhouse Lane, Marlow, Buckinghamshire, SL7 1HY.
