Challenge/Response Spam blockers

[List Maintainer <jimo@xxxxxxxxxx>]

It has come to my attention that some list subscribers who are using
challenge/response spam-blocking systems are causing C/R requests to
be sent to posters to this list.  

This practice is absolutely not allowed; if you use a C/R system, it
must whitelist the LIST's envelope-from address,
omega-list-request@xxxxxxxxxx, which is the agent through which all
list articles are resent, or one of the other headers listed below,
and must NOT annoy the authors of those articles. 

To this end, I'd appreciate hearing from any list posters who receive
these C/R requests, so I can remove the offenders.  As always for
admin issues, it's helpful to include the full headers of the
emails in question, particularly the Received: headers.

For the record, the best headers to use to inform filters of omega-
list traffic are, in decreasing order of preference:

  Resent-Sender: omega-list-request@xxxxxxxxxx
  Resent-From: omega-list@xxxxxxxxxx
  X-Mailing-List: <omega-list@xxxxxxxxxx> archive/latest/<nnn>
  X-Loop: omega-list@xxxxxxxxxx
  Return-Path: <omega-list-request@xxxxxxxxxx>

You are virtually guaranteed to never get any of those headers in
non-list email, though I suppose some spam pseudo-smtp servers may
try to forge the return-path.

Thanks,

Jim