* Brandon D. Valentine <brandon AT dvalentine DOT com> [2004-01-19 20:56]:
> 
> I sort amanda-users based on the Sender header.  Most older
> Majordomo installations don't offer any of the List-* or X-*
> headers, but Sender has been available via Majordomo for some time.
> 
> Here's procmail:
>       
>       :0:
>       * ^Sender: owner-amanda-users
>       amanda-users

Thanks for all the feedback folks, it turns out I was on another list
that has only a "sender" identifier, and I was filtering it based on
TO/FROM parameters, which fails when you get users who BCC.  I wrote
with the following generic recipe that works well for this list:

  SENDER_ML=(\
  owner-amanda-users@amanda\.org|\
  owner-cryptography@metzdowd\.com)
  
  # Sender is owner mailing lists
  #
  :0 :
  *$ ^Sender:.*$SENDER_ML
  * ^Sender:.*owner-\/[a-z0-9.-]+@
  * MATCH ?? ()\/[^@]+
  mailing_lists/$MATCH

This basically files mail in 
  ./mailing_lists/amanda-users and
  ./mailing_lists/cryptography.  

The nice thing is that for other such lists, there only needs to be a
one-liner added to the SENDER_ML variable, which keeps the code
condensed.

I still haven't come up with code to handle cases where users ignore
the mail-followup-to field and send me two copies.  The dupe filter
just kills which ever copy comes second, which unfortunately is
sometimes the list reply.

Anyway, sorry if this is getting OT.. I just thought some folks here
might find this code useful.