Spamato4Thunderbird needs Java 1.5 (or higher). It has been tested on Windows and Linux. See our installation guidelines if something seems to be odd: http://www.spamato.net/index.php?option=com_content&task=view&id=32&Itemid=65
Spamato is hosted on SourceForge: http://sf.net/projects/spamato. Please write to our forums if you have any questions.
Spamato also exists for Microsoft Outlook, Mozilla Mail (old versions), and as a stand-alone proxy (for all other email clients, e.g., Outlook Express, Eudora, IncrediMail, ...).