Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!panda!talcott!harvard!seismo!brl-tgr!tgr!wales@UCLA-LOCUS.ARPA From: wales@UCLA-LOCUS.ARPA (Rich Wales) Newsgroups: net.mail.headers Subject: Re: Subject: Ambiguity with the REPLY-TO field Message-ID: <11584@brl-tgr.ARPA> Date: Mon, 15-Jul-85 12:21:14 EDT Article-I.D.: brl-tgr.11584 Posted: Mon Jul 15 12:21:14 1985 Date-Received: Wed, 17-Jul-85 21:12:45 EDT Sender: news@brl-tgr.ARPA Lines: 85 Jacob -- I thought of another way of describing the RFC822 semantics of REPLY-TO last night, after I sent my reply to your original message. It may seem a bit backwards at first, but I think it makes the situation somewhat clearer than the traditional perspective. (1) Think of *every* message as *always* having a REPLY-TO field -- at least conceptually. Consider that RFC822 has provided a short-cut in the interests of brevity and non-redundancy in message headers. Namely, if the "Reply-to:" header line contents are identical to the "From:" line contents, then the "Reply-to:" line can be (and probably will be) omitted from the header when the message is sent. The receiving end, on finding that a message has no "Reply-to:" line in its header, will implicitly create a REPLY-TO field by copying the FROM field. If you assume in this way that *all* messages have REPLY-TO fields, the rules for constructing the recipient lists for replies suddenly become much simpler and more straightforward. (2) Automatic replies *always* go to the addresses in the REPLY-TO field (which, by the above assumption, always exists in every message). The FROM field is *never* considered when addressing a reply. To be sure, the REPLY-TO field may have been implicitly derived from the FROM field when the message was originally read and the header was parsed -- but once this operation has been done, we simply concen- trate on the fact that the message has a REPLY-TO field, forgetting completely about where it came from. (3) You can then distinguish, if you wish to, between "personal" and "group" replies in the following way: (a) "Personal" replies would go only to the address(es) in the REPLY-TO field. (b) "Group" replies would go to the address(es) in the REPLY-TO, TO, and CC fields. It is debatable, by the way, whether a "group" reply should also go to the SENDER address(es); Section 4.4.4 (page 22) of RFC822 states that the SENDER field should never be used automatically when replying to a message. I would suggest that the SENDER field be included in the address list of a "group" reply only through invocation of a non-default option, if indeed at all. You expressed some confusion/concern over whether RFC822's semantics of the REPLY-TO field envision the use of this field in "personal" replies or in "group" replies. I think what happened was that RFC822 assumed that the message *author* -- *not* the recipient -- would make the deci- sion as to who would receive replies. At the time (and probably even now), most people were accustomed to mail systems where the only kind of reply was what you term a "personal" reply (i.e., to the author of the message and no one else). The REPLY- TO field was apparently envisioned as a way to allow the message sender to specify a wider audience for any replies to his message, without having to assume that the person at the other end had a mail system capable of automatically constructing a "group" reply (since most people didn't have such mail systems anyway). Hence, RFC822 does not really seem to provide for the kind of distinc- tion between "personal" and "group" replies which you would like to make. Clearly, the issues involved were not fully appreciated, and had not been thoroughly thought out, when the standard was written. My making this observation is not so much an indictment of the people responsible for RFC822 (who, I think, did a very good job considering the constraints they were working under) as it is a realization that our understanding of the possibilities of electronic mail has kept on expanding. I think this is a good occasion to renew my suggestion that some person or group should investigate issues such as these, and make sure that the various kinds of recipient lists (personal replies, group replies, con- ferences, etc.) can be adequately represented in X.400 or other appro- priate international standards. -- Rich Wales // UCLA Computer Science Department // +1 213-825-5683 3531 Boelter Hall // Los Angeles, California 90024 // USA ARPA: wales@UCLA-LOCUS.ARPA -or- wales@LOCUS.UCLA.EDU UUCP: ...!(ihnp4,ucbvax)!ucla-cs!wales