Well in that case then
http://spamassassin.apache.org/ Be sure to check the FAQ about using SpamAssassin and Documentation. Not too sure why you need, enless your running a mail/web server? Are you using Evolution Mail? What issues are you having on your workstation? We are here to help... Please note that I personally expect Ubuntu to become more spammed as it seems inevitable with the direction they are going. Here's some info on spamassassin on Evolution:
1 Launch the Synaptic Package Manager by selecting "System," "Administration," "Synaptic Package Manager."
2 Type "spamassassin" into the search box at the top right.
3 Right-click the package "SpamAssassin" and select "Install."
4 Click "Apply" to install the package.
5 Launch Evolution by selecting "Applications," "Internet," "Evolution Mail."
6 Select "Edit," "Plug-ins."
7 Ensure that "SpamAssassin" is checked and click "OK."
8 Select "Edit," "Preferences" and select the "Mail Preferences" tab,
9 Ensure that "Check incoming messages for junk" is checked and click "OK."