> No, the list is still dumb. The post which was supposedly a duplicate was
> my first in months. I sent another copy because the list told me that my
> first post was rejected. To accept and propagate the message while telling
> me that it did the opposite is clearly and unequivocably dumb.

I have a very strong suspicion that there is an address subscribed to the
list which is improperly bouncing messages such that the server doesn't
recognize them as bounces.  Thus, the sequence is:

  Your message goes to server
  It goes from there to everyone, including the failing address
  The failed address bounces
  The server sees the bounce and generates a "duplicate posting" message
    which it then sends to you [apparently the machine at the bad address
    munged the addresses in the message such that the server thought its
    bounce came from you].
  You see the "duplicate posting" message . . .

I think the best solution to this problem would probably be for the list
maintainer to send a message to all people on the list asking them NOT to
reply if they received the message, with the From: and Reply-to: set to
the list maintainer (not the list itself!).  This would then allow the
person maintaining the list to identify any addresses which are bouncing
and unsubscribe them from the list.

Does anyone see any problems with this strategy?