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My GSM Treo 600 with AT&T Wireless service is, IMHO, the first essential smartphone. Even with the amount of effort to get it configured, it’s a net benefit to your daily life. However, international travelers know that one of the great features of GSM is being able to buy prepaid cards with a local number in whatever country you’re visiting (Croatia, Ecuador, Morocco…). That way, people you’re interactining with in the country don’t need to call a long distance number in the States, you pay reasonable prices, and you don’t get waken in the middle of the night with an office worker calling about a minor issue.

AT&T locks their phone to make this impossible, which is especially ridiculous since I already signed up for a year service package. Thankfully, people on treocentral have figured out how to crack the lock.

The file is currently available from here (updated). If this link breaks, go to TreoCentral and search for “patched.zip”.
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Update 2005-04-17: Please also check out using IMAP for learning and the wiki entries on ProcmailToForwardMail, (which contains a slightly updated script) and the very detailed directions at SingleUserUnixInstall.

SpamAssassin is currently the most effective spam filter. For me, it correctly marks several hundred messages a day as spam, with nearly no false positives, and only a couple false negatives. Those false negatives — spam that gets through — should be avoidable by training the Bayes algorithm that SpamAssassin uses. Unfortunately, using Outlook working with Exchange server as my mailer makes this incredibly hard to do.

Note that Bayes does not need to be hand trained in order to work well. The magic of SpamAssassin is that the Bayes bootstraps its learning off of the several hundred non-Bayes rules, including the use of DNS blocklists. So, spammy messages that hit certain rules train the Bayes to find similar spam in the future even that doesn’t hit those rules. Thus, the purpose of this procmail rule is simply to enable mistake-based training, which catches the small percentage of false negatives that might otherwise slip through.

Like many SpamAssassin users, I forward my mail through a Unix account, where I’ve configured procmail to filter the message through SpamAssassin and then forward it to my private address on another machine.

The trick for Bayes training is to add some extra procmail rules to specify special processing for training messages. The following is based on having a catchall address for all mail sent to example.com, so I can trigger the bayes training by sending mail to spam@example.com and ham@example.com. It is left as an exercise for the reader to create an alternative script that triggers based on a passphrase added to the subject, and uses formail to remove that passphrase before passing the message to sa-learn.

Note that this setup still only works passably with Outlook and Exchange, because even resending the message causes a new Message-ID header to be created and the old Received headers to be lost. Other headers are still carried over. To trigger Bayes learning from Outlook on false negatives, choose Action: Resend this Message (you have to remove any From and CC headings and change the To field to spam@example.com). Note that nearly every other mailer (except for AOL) supports real redirects; see the bottom of this site.

Here’s the .procmailrc:
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