I have a list which is configured to aggressively filter out certain
types of message encodings and content, partially using the spam
filtering capability. (We have a LOT of people using very old command- line software to read e-mail, so we keep anything out which can't be
viewed that way.) Since list subscriptions are open, and we allow
contributions from non-subscribers after moderator approval, there
are a lot of posts from non-technical people who have no clue that
there is even a difference between types of e-mail message, let alone
that it might be desirable to use the simpler kinds. Although we send
out instructions including a link to the excellent page at http://www.expita.com/nomime.html to subscribers, not everyone who posts has subscribed, and I fear
that most subscribers don't read the message in the first place. The
upshot of this is that I receive many messages from people who have
received "filter rule match" rejection notices, asking what to do. Is
there any way to provide a custom message in place of "filter rule
match" for spam filter rejections?

-John Franklin