Reports of procmail's death are not terribly exaggerated

Hell, not only do you need regexes, you need the ability to run arbitrary programs and make decisons based on their exitcodes, or, possibly, command-line output: allowing shell fragments, or something like them, works well here. You need the ability to do *multiple* things if a test passes or fails, which means you need conditionals and a block structure.

The syntax may be rebarbative, but procmailrc surely is a language.