On Tue, 6 Nov 2007, Michael Haardt wrote: > All in all, it is absolutely worth the hassle. For me, it catches 1/3 > up to 1/2 of all spam at minimal cost.
And don't forget that mail you don't want to receive will likely match several of your ACL checks. So if refusal on the basis on no or mismatched DNS makes you a little nervous, put the check after other checks you are already happy to use, such as DNSBLs, HELO checks, RCPT checks, local blocklists/whitelists and so on, so that 'suspicious' mail already has a chance to fail for other reasons. I found putting a refusal based on no/mismatched DNS early on caught lots and lots of stuff (that would probably later be caught be DNSBLs etc). Putting it towards the end it was much quieter, and much easier to monitor for likely 'false positives' (in the sense that it was mail we would probably have wanted to accept had DNS been consistent, not obviously spam anyway). Or you could combine the check with other checks that make you a bit nervous, in the hope that a message matching several anomalies all at once is probably not worth accepting. Or mark it and pass it on to SpamAssassin for more prejudicial scoring. Jethro. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jethro R Binks Computing Officer, IT Services University Of Strathclyde, Glasgow, UK -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
