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Call for papers

Free (or nearly Free) Spam Reduction with PF and Spamd

Spamd is a small, non-forking minimal smtp implementation used for spam deferral. It can be used both to blacklist connections to a tarpit for known spam sources, or greylist smtp connections from previously seen MTA's.

Like many common greylisting implementations, spamd will greylist based the incoming tuple of connecting IP address, envelope-from, and envelope-to addresses. Unlike many other greylisting implementations, spamd uses the packet filtering mechansims in pf to control the greylisting of mail connections, and whitelists known MTA's, once seen.

Best of all it's MTA independant, so you don't need to either run it on your MTA, or take a load for doing greylisting on your MTA box. All you need do is put it on a firewall in front of it. As such in typical setups we have found it will reduce the amount of mail that will need to be recieved by a mailserver by 60% or more in practice, with practically no collateral damage.

This paper will cover the concepts of greylisting and blacklisting, compare spamd to other implementations, and cover current and future feature sets. It will also discuss the setup of a large mail cluster using spamd and pf, as well as various statistics seen for various spam blocking tactics in the wild (including Caller-ID/SPF), particularly to address why spamd does and does not implement certain tactics for spam blocking.

speaker: Bob Beck

location: SITE G0103

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