SpamAssassin is slightly different from most of the software that is used in this book. It is written in a language called Perl, which has its own distribution method called CPAN (Comprehensive Perl Archive Network). CPAN is a large website of Perl software (normally, Perl modules), and the term CPAN is also the name of the software used to download those modules and install them. Though SpamAssassin is provided as a package by many Linux distributions, we strongly recommend that you install it from source rather than use a package. This way, you will get the latest version of SpamAssassin rather than the one that was current when your Linux distributer created its release.
Most Perl users will build Perl modules using CPAN and experience no difficulties. CPAN can automatically locate and install any dependencies (other components that are required to make the desired component work properly). From a Perl point of view, using CPAN to install Perl modules...