A dusty little corner of the Internet: electronics, computer hardware and software, general aviation, 1980's Mopars, and related sundry.
cats2procmailrc is a tool written in Perl by Cameron Simpson. It reads a human friendly mail category description file and emits a matching procmail recipe to implement it. The intent is to have an extremely succinct file of easily editable one line rules, generally of the form:
folder tag pattern
See the man page for more information.