I was a great fan of Kmail email program, but recently I have to use Mozilla Thunderbird (manly because now I’m cross platform AND cross OS: Kmail is only for the Linux/KDE flavor). Thunderbird is powered by a great spam (junk) mail filter: you can enable it from the account’s options for each account.
The cool stuff is the customization level of this spam filter: after enabling it, you can also train it, so it can learn, day by day, what kind of email you consider SPAM (the Bayes Junk Tool uses a very complicated method to achieve this goal, evaluating also yours typical email subjects, senders, etc…).
The useful thing is the possibility to train one client and migrate to all your systems (eg from the laptop to the desktop): after setting up all yours account and identities you have to copy the training.dat from the working Thunderbird client to the new one.
Under OS X you can find the training.dat file here:
Under Linux you can find the training.dat file here:
Under Windows you can find the training.dat file here:
c:Document and settings$userThunderbirdProfiles$random.default
Happy filtering! 🙂