Josue Salazar has a problem with Gmail’s spam filter.

After switching from Mail.app to the web-interface to read his Gmail, something odd began to happen:

I started to notice 90% of the email in my Gmail inbox was spam. I marked it as such, wondered what was going on, but in the end I just moved on.

Today, I realized there was something wrong…. I decided to take a quick look at the Spam folder. As expected, all the emails I’d marked as spam on my inbox were there, but to my surprise so were tons of emails from my contacts, and two job offers from days ago. What the hell?

Josue emailed asking if I would mention this onslaught of false positives “to see if someone else is having the same issues I am, or if it’s just me seeing things.” I don’t know the answer, not using Gmail as much as I possibly should.

Dr Drang has a suggestion about how Gmail’s spam filtering could be improved. He is fairly happy; Gmail catches 85% of his spam, but he worries about the other 15%, most of it not in English. It could be solved, he suggests, by

the ability to filter based on the character set used in the message. I cannot read anything written Asian or Cyrillic characters and no one I know would send me such a message, so it must be spam. Back in my Linux days, I used the procmail filter given in the Bogofilter FAQ to eliminate Asian spam before my spam filter even saw it…. The Google folks are generally considered the smartest working on the web today; they should be able to whip up a character set filter in no time.

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Steve Dispensa tells a funny story at Kernel Mustard:

My Apple mail client has a built-in spam filter. I’m not sure how it works, but it does have to be trained. Anyway, that’s all I know about it.

It turns out that of all of the copious communications I receive from Microsoft, the ONLY thing that the spam filter catches - EVERY TIME - is the Microsoft Mactopia (Mac Business Unit) newsletter. I mark it as “not junk” every time. It refuses to learn.

(For what it’s worth, Mail.app is largely a piece of crap, with tons of un-Apple-like bugs. Don’t get me started.)

False positives are annoying. But my Mactopia newsletter turned up without problem in my Inbox this morning, so it doesn’t have to be this way.

Three ways to reduce false positives:

1. Keep your Address Book up to date. You can set the Junk Filter to let through messages from people whose email addresses are in your Address Book (Preferences > Junk Mail > Sender of mail is on my Address Book), but it only works well if all the addresses you value are in it. (Could this be Steve’s problem?)
2. Make sure that you always correct the Junk Filter if it incorrectly marks a message as Junk Mail by clicking the “Not Junk” in the Toolbar or hitting Command-Shift-J. This ongoing learning stops Junk Filter making the same mistake more than once.
3. If nothing else works, create a rule for email that Junk Filter keeps wrongly marking as spam. Add the “Stop evaluating rules” action to the rule and Junk Filter will ignore the email.

These excellent tips are taken (shamelessly) from Joe Kissell’s “Take Control of Spam with Apple Mail” ebook. Buy it .

It makes an first-rate companion to his equally-useful Take Control of Apple Mail in Tiger ebook. Or save money and buy them both .

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