[Dennis Oelkers <oelkers / zrz.TU-Berlin.DE>, 2004-06-03 16.18 CEST]
> Hello David, ruby-talk, c.l.r.,
> 
> David A. Black wrote:
> >The remaining problem seems to be subject lines with "Re:" in them,
> >when there are no In-Reply-To and References: headers.  This
> >apparently makes the NNTP server flag the message as a followup and
> >then be unhappy because there's no reference.  
> 
> My further investigations proved that this is really the problem. The
> symptoms are the same as with the first problem (I get a 441 - "Followup
> without a reference" - when posting the mail to the newsgroup), but this
> time the solution is non-trivial. The first case ("In-Reply-To" flag in
> header but not "References" flag) was solved by adding the missing flag
> by duplicating the message-id of the "In-Reply-To" flag. In this case
> both flags are missing. The MUA which was used by Austin Ziegler adds
> "Thread-Topic" / "Thread-Index" flags to the header which are supposed
> to solve the threading, but this is not applicable to Usenet.
> 
> This leads to the conclusion that we have three possible solutions:

I suggest another: if the message subject begins with "Re: " or "re: ", but
doesn't have a "References: " header, change the "Re: " to "RE: ".

If it has a "References: " header, but the subject doesn't begin with "Re: "
or "re: ", add "Re: " at the beginning.

I think that should satisfy RFC 850.