I get a lot of spam mails. Many of them are blocked by the spam filter of my email provider. But quite a lot still come though. Although I had used Thunderbird under Windows I switched to Kontact/Kmail under Linux as I liked it better. And I'm still using it although I have the Gnome version of Mint 9. Since Kmail doesn't include a spam filter by its own I used Spamassassin (with the pyzor and razor plugins) and Bogofilter - both available from the repos. Once installed, Kmail can automatically integrate them and configure appropriate rules. While the results were satisfying, Spamassasin slowed down Kmail consideraby. So I deinstalled Spamassassin finally and added crm114 - also available from the repos - instead which is also automatically recognized by Kmail. Nevertheless, configuring that program is a bit difficult at first - fortunately I found an article that explains it well. If you read the pdf article you should start with "Setting up the mail filter" on page 75. And you should also make sure that you add the filter rule mentioned in the 3rd column on page 77 to the default rules. All this has to be done only once. Applying crm114 thereafter is very easy. Although Spamassassin theoretically offers some benefits over Bogofilter and crm114 (since it offers more than "just" Bayesian/statistically based filtering) I don't miss it at all. After some training practically all spam mails are recognized with an extremely high reliability. And the performance of Kmail has improved considerably.