On Fri, 11 Jun 2004 11:50:26 CDT, "Laurence F. Sheldon, Jr." said:
Where is RFC 2821 is this requirement, by the way? RFC 2822 says it is optional but seems to be less than useful in the context here.
2821 is about the SMTP side of things. By the time the MTA is handed a list of RCPT TO's, it's waaay past time to argue about Reply-to:. (As a matter of fact, careful reading of 2821 will reveal that there's no *specific* requirement that the stuff between the DATA and final '.' even be an 822-style e-mail - I've seen blecherous things that toss an X.400 blob around in there instead...) 2822 and related would be the right place, as that's about the 822-style headers on the mail itself. As already noted by several people, Reply-To: doesn't necessarily impose the proper semantics (and before anybody pipes up, Bernstein's "Mail-Followup-To:" isn't perfect either, *and* there's not even an active I-D for it, much less any sort of RFC).