Filtering junk on inn-bugs

[Forrest J. Cavalier III]

Most of the junk email I receive I never even see.  (60-80%
is deleted, and I am a fanatic about reducing false positives.)

It is apparent that most junk that makes it through is
mail sent to open mail lists which are in my whitelist.

inn-bugs at isc.org is in my whitelist and is adding an
increasing amount of junk to my inbox.  (About 5 a day
last week, but yesterday there were 12.)

I think the inn-bugs@ is an important list to monitor.

Upon inspecting the junk received that way, my first attempt
at filtering is rejecting messages also To or CC to
a -request at isc.org address.  (This rejects about 50%
of the junk recently sent there, and will NEVER have
a false-positive.)

I'd also like to reject all HTML email there, since
that is highly unlikely to have a false positive.  But
Ecartis apparently tries to be "helpful" and creates
a text version of HTML email.  Is anyone considering
turning that off, or returning HTML email as undeliverable?
Can E-cartis add a X-Original-Content-type: or something?

Anyone else have suggestions for filtering junk from email
sent to open list addresses when reducing false positives is
crucial?  inn-bugs@ is not the only open list I subscribe to.

Thanks for ideas.

Forrest