If like me you have tried (and failed) to build Spamassassin on Solaris the following may help, read it all before you start compiling.
When you follow the SA build instructions you will get a warning message that HTML Parser is missing, even if you have no idea what this is you have probably guessed that a spam filter which cannot read HTML may be somewhat useless.
HTML Parser is in fact a Perl module which can be downloaded and built, it has one dependency HTML Tagset which you should build first. Before you do any of this we need to make some modifications to the Sun installed versions of Perl5. These versions were built with the Sun Compiler, if you are using gcc to build the modules then the modifications are required, if you are using the Sun Compiler then this page is not for you.
Solaris 9 has two versions of Perl, 5.00503 and 5.6.1 we need to modify the Config.pm files found in
/usr/perl5/5.00503/sun4-solaris/
and
/usr/perl5/5.6.1/lib/sun4-solaris-64int/
Here is a modified version for 5.00503 and Here for 5.6.1 rename both to Config.pm and copy to the above locations, rename the originals first.