Domain: rhyolite.com
Stories and comments across the archive that link to rhyolite.com.
Stories · 3
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Computationally Cheap Spam Filtering?
Roadmaster asks: "Usually, the most effective spam filtering techniques are somewhat resource intensive. Heuristic checkers like Spamassassin, or bayesian filters like spamprobe are processor and storage hungry. This is fine for small setups; I've been using spamprobe to filter spam for 3 users with great results. I'm now however faced with a big challenge: a mail server that will eventually be handling mail for over 50,000 users and needs to have some sort of anti-spam measures. What are some good and computationally cheap spam prevention measures?""Ideally, I'd prefer something that does reject the message if it's spam (SMTP result code 550 or something like that), unlike current Spamassassin or spamprobe setups that accept the message and only later decide whether it's spam. Solutions like MAPS RBL, ORBS are acceptable altough commentary on their accuracy would be welcome. Other possibilities I've thought of include checksumming (Vipul's razor or DCC) and simple header checks that could be implemented for instance in a sendmail milter.
Are several quick checks (DCC + RBL) accurate enough and still cheaper than one slow check (Spamassassin, bayesian filtering)? does stacking of similar techniques improve accuracy significantly? (DCC + Razor, RBL + ORBS). How can the good but expensive techniques be made cheaper? (Spamassassin's spamproxyd, hashed wordlists for bayesian filters, and so on). Discussion on all these aspects would yield some interesting conclusions on quick and efficient spam filtering." -
Fighting Spam on the Home Front
Saint Aardvark writes: "Something interesting from the SecurityFocus Honeypot mailing list: a couple of honeypots for spammers. This message has a link to a how-to page for setting up a Sendmail honeypot to trap spammers, and the status page for a honeypot in Moscow that's trapped spam meant for >1.7 million recipients. The author mentions using a honeypot in conjunction with the Distributed Checksum Clearinghouse -- this seems like a great way identify both spammers and their messages."And C-Moan writes: "Wireless spam volume is likely to increase in the coming years. But smart use of spam-fighting measures can go a long way toward eliminating the problem. This article provides info about the latest crop of e-mail filters and enhanced mail client options, as well as two roll-your-own programming platforms that could help keep your in-boxes spam free."
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Distributed Checksum Clearinghouse vs Spam
AllSpammedOut writes: "Spam could be more easily detected if everyone were to compare the mail messages they received. Using the Distributed Checksum Clearinghouse, MTAs can report the checksums for all messages they receive and be notified when a checksum has already been reported by many other systems." Obviously there are issues with something like this (especially mailing lists, and worms that do attachments). I suspect spammers would just include a counter to break checksums tho."