Jason_Meers wrote: > Hi all, > > This is a new post quoting a section of a previous post. > > -snip- > Background: > The idea is to develop a config that could determine which MX record had > been used to make the initial connection (by getting the firewall to > forward the SMTP conversation to different ports on the same server, > based on the IP address the connection initially came in on). > This would avoid having to have a dedicated box and dedicated config for > each MX preference. > -snip- > > > I'm seeing a lot of junk-mail deliberately going for the lower > preference MX records first (by lower preference I mean MX records with > a higher numerical value than the others). The thought is to be more > strict/thorough about checking connections that are initially made to > the "wrong" MX (because I don't expect this of a "genuine" properly > configured MTA). > > Is it acceptable to just dump connections that make no attempt to follow > the RFC's and go directly for the lower pref MX's.
Not really.... see below... > I have 5 other boxes > (in separate locations) that _should_ have been tried before anyone > would have a valid reason to connect directly to the lowest pref box. > > Is anybody else already doing this? > Does it work for you? > > Thanks > Jason_Meers > > Mark Perkel has posted a great deal about his methodology of using 'bait' MX cleverly to trap/divert spam. Personally, I think that approach just 'plays' with spam sources that can easily be blocked by simpler means (lack of a PTR RR and/or dynamic IP RBL-hit at the top of *my* list. YMMV). But the larger issue is that if you *publish* a DNS entry for an MX - regardless of its priority - then you should damn well be prepared to accept 'normal' traffic on it. ELSE - don't publish it, as you are contributing to breaking RFC-mandated behaviour for the many who *need* backup MX to function as expected. Spam is by no means the only driver for selecting a lower-priority MX, and two wrongs don't make a right - complaints or lack therof notwithstanding. Bill -- ## 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/
