This is a mail robot which one can use to insert incoming mails into a mysql database maintained by phorum(TM). In other words, phorumail.pl is mail backend to phorum(TM) which allows you to post to an online forum via mail too. The current phorum(TM) distribution contains already a script called "phorumail", but it's written in php and requires an php-interpreter installed, which is not the case on most hosts I know of.
This script is based on an older one (with the same name) from Dana Basken.