It was an Internet-wounding error not to include a remote-upgradeable spam protection product in Movable Type from the beginning. Spam-ridden, abandoned MT sites are metastasized cancers in the web that Google and its ilk must now route around, to their increased cost and to the detriment of adding more useful features to search.
Nevertheless, the addition of SpamLookup to my longstanding MT-Blacklist installation has created a silver bullet against comment/trackback spam on my site. While I get thousands of spam attempts a week, the number getting through is now zero — and the number that get automatically moderated and thus require me to scan them is down to a handful. It’s a huge productivity tax cut.
By way of background, Jay Allen’s MT-Blacklist is a constantly growing library of known URLs and spam strings, while Brad Choate’s SpamLookup is a set of tricks for detecting some well-known spam practises, from using proxy servers to trackback-domain mismatches. A closing cautionary note: While these have solved my problem, cleaning up all those unprotected and broken MT distributions out there will eventually require hosting services to go in with a machete & kerosene.