On Tue, 2022-05-10 at 18:19 -0600, Philip Prindeville wrote: > I can't think of a single way to match each header, and then test for > any of them not matching the pattern... > > I had in mind a subrule that triggers on valid header names, combined with a meta rule that inverts the subrule result. At least, that's what I'd try as a starting point.
Martin