On Mon, 2011-11-14 at 05:35 -0800, Marc Perkel wrote: > I'm still playing with this. Probable also need to reduce or eliminate > caching on the recipient callout. But I thought I'd post it in case > someone finds it useful.
It's a fairly old technique but it's hidebound by problems - probably more than it solves. You can never assume that an inbound SMTP connection to a lower priority MX server is coming in when the higher priority server(s) is (are) up means that the inbound message is spam. It may be so that there's a higher probability that it is, but consider the fact that there are an infinity of reasons why a given host can't talk to your higher prio MX. Network interruptions are the principal cause, but also the higher prio could have deferred or refused the connection due to a volume of inbound messages. That doesn't mean it's down, but is in self-defence mode - and in many cases, will still be accepting from the lower prio MX servers *especially* if you're doing call-forward to them! It can be a useful scoring method, but you cannot absolutely assert that the inbound message is spam. Be prepared for false positives if you use this technique to make that assertion. Graeme -- ## List details at https://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/
