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Paul Graham: Filters that Fight Back
Mortimer.CA writes "Paul Graham is back with another article about combating spam. It's entitled Filters that Fight Back: 'One intriguing idea is to literally fight back: to make filters disable spammers' servers by automatically following all the links in each incoming email. We may be driven to this in order to achieve accurate filtering anyway. Why wait?' One danger is someone doing a DDoS by sending fake spam."
I recently switched from a keyword-based spam filter to a bayesian filter. However, there exists several bayesian filter projects and the choice of which to use is not obvious. Therefore, I decided to do an actual test and write up my findings in a review so others can benefit as well. Read it and find out how to win the War on spam.
You can have a domain/subdomain with no A records or MX records and they will keep trying. You can also have nothing but blackhole MXs - hosts that don't exist, but are on routable networks. I've had a domain since 1994, and it was in one of the above states for about 2-3 years.
Last month I put a real MX record in there and pointed it at box that's running a mail server. Sure enough, the spam flows continuously. It's not just the "make up random shit and put @aol.com" idiots either - the big outfits with permanent networks and domains are mailing it too.
I've taught my mail server to quarantine any host that attempts to mail my long-dead domain, so having it go to a routable address is actually useful again. Every attempt they make ruins another open proxy or relay for every other spammer that may find it later.
You might consider using those "never valid/previous owner" accounts as spam traps. Anything coming to them now is obviously worthless, so why not make them suffer for trying?