A few things actually…

• First, POPFile is not tied to a certain brand or type of email client or server.
• POPFile is written in Perl. As Perl is available for a wide array of platforms, POPFile is compatible with a very wide array of computers.
• It is a highly configurable email classifier, not simply a spam filter. Email can be classified to any number of categories you define.
• POPFile uses pseudowords to handle various message elements and spammer tricks to help improve accuracy.
• POPFile doesn't use heavyhanded approaches like blacklists or excessively openended approaches like whitelists, both of which can be problematic when they make a mistake.
• As a general mail filter, it stands out from the crowd as it has the capacity to learn, and learn quickly.
• As a spam filter, it stands out due to its high accuracy and elegance through simplicity in design.