Kiwi spam filter gets few wrong

Another locally developed anti-spam tool is in beta testing with a likely release date of later this year.

Another locally developed anti-spam tool is in beta testing with a likely release date of later this year.

Death2Spam (D2S) features a filter with “learning” capability, and currently operates in an application service provider mode. “There is no need to install any software on your PC,” say the release notes, but the ASP connection pauses uncomfortably at times when downloading email on to the desktop.

D2S was developed by Richard Jowsey, who claims 30 years of internet programming experience including periods of work in Seattle and Sydney.

Jowsey is described by his brother Mike, spokesman for the project, as being “sorely vexed at the takeover of good mainstream internet space by an out-of-control mass-marketing machine”.

Emails downloaded from the mail provider through the D2S server to the local PC are marked [spam] [good?] or [???] in the header, or left unmarked (judged unambiguously “good”). Simple configuration of the email client (D2S works with major clients such as Outlook, Lotus Notes and Eudora) ensures that all messages marked [spam] are automatically put in the trash or other suitable folder.

While accepting regular email addresses, D2S chokes on my main home address, an eccentric format with bell/s.bell@..., indicating a sub-mailbox in the family mail-space. This problem has not, at date of writing, been solved.

After downloading mail, the user can then visit his/her account on the D2S server, view the messages sorted into “spam”, “good” and “unsure” boxes and reclassify with a click the “unsure” emails, and any the program has put in the wrong box, before deleting received messages from the server.

The learning algorithm appears quite effective. When I redefined messages from various contributors to a mailing list as “good” rather than “spam” it took three iterations to get D2S passing them all through faultlessly. I then decided I might want messages on a particular subject that it had been used to marking as spam, and I began reclassifying them all as “good”. I then took a subset of those and re-re-classified them as spam.

Again, D2S took two cycles to get the first reclassification right almost all the time and three to pass all reclassified messages correctly. At time of writing it’s still learning the subtler re-reclassification, but after three cycles is getting very few wrong.

Once settled down, the filter is still prone to the occasional “blooper” — passing a no-effort college-degree offer and a porn mail with illustrations and a text that got a two-chilli mark (maximum three) in Eudora’s rude-language monitor. It also passed one virus-infected executable attachment, but Norton AV picked it up. It would be misguided to rely on a spam filter for virus detection.

I can’t report on its efficiency at fingering fraudulent Nigerians because the two mail accounts used for testing have amazingly received none of those during the test period so far.

D2S invites comparison with the popular locally produced Mailwasher, whose

spam discrimination capability I find comparatively crude and labour-intensive.

Mailwasher, however, allows messages to be dealt with on the server, while D2S in its current version requires them all to be downloaded first. When this was pointed out to the Jowseys, they modified the program so the body of a spam message was deleted and replaced by the phrase “Death to Spam!” This saved on email volume, but made it nearly impossible to retrieve the body of a wrongly spam-marked message. A further fix is in train, says Richard Jowsey.

Mailwasher allows message bodies and complete headers to be examined before taking delivery. D2S lacks this facility.

A nice D2S feature is the ability to delete a whole page of spam messages off the server with one click. Ticking them all off one by one in Mailwasher or on is a pain.

I don’t really see much point in the ASP orientation, though. It allows multiple users’ evaluation of “spamness” to be pooled; but, on the other hand one person’s spam and another’s valued and solicited information might have very similar wording. Death2Spam might productively be offered in an alternative version as a desktop- or LAN-server-resident application.

Email Stephen Bell

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