> How about using the USENET keyword of NEWSGROUP: and making that a
> replyable field with a higher priority than that of Sender: for
> notification/rejection purposes. Not that I intend to redefine the
> way that RFC822 works - but if MAs like MAILBOOK are going to be
> picky - then I consider it our duty to find a way around it in order
> to keep a more efficient distributed-mail-network. yes?
>             - Michael Gettes, Boston University
> I guess this is meant for Eric since he is the only one responding.
 
That seems backwards to me.  Sender ought to be used for its RFC822
purpose, which is essentially the place that rejection notices are
supposed to go to.   I am in favor of introducing the Newsgroup
header to indicate what list the message is from.  We would modify
our user agent to look for it.