Some statements have been made about use of Reply-To; that
its use to direct responses to a mailing lists precludes indicating
a preferred mailbox for direct responses to the author(s), that
it provides no mechanism for indicating why a suggestion is
being made, that it provides no mechanism for an author to
offer guidance to a potential respondent who wishes to direct
his responses elsewhere. I will address those issues in this
message. There are several reasons why an author might
suggest a place for responses; RFC 822 lists three, and I'll
use those three:
Three typical
uses for this feature can be distinguished. In the first
case, the author(s) may not have regular machine-based mail-
boxes and therefore wish(es) to indicate an alternate machine
address. In the second case, an author may wish additional
persons to be made aware of, or responsible for, replies. A
somewhat different use may be of some help to "text message
teleconferencing" groups equipped with automatic distribution
services: include the address of that service in the "Reply-
To" field of all messages submitted to the teleconference;
then participants can "reply" to conference submissions to
guarantee the correct distribution of any submission of their
own.
For brevity, I'll refer to those as "alternative", "delegation", and
"list", and when discussing combinations, the individual cases
will be numbered based on bitwise combinations of those three
assigning binary power values 4, 2, and 1 respectively.
The claim that use for lists precludes use for alternatives presumes
that combinations of uses are not possible. That is not necessarily
true for all combinations; moreover it ignores other mechanisms
available. Given the three uses mentioned above, there are a
total of 2 raised to power 3, or 8 possible combinations:
0: some use other than the three listed; i.e. none of those three
1, 2, 4: these are single use cases. 1 and 2 are straightforward,
but case 4 warrants some additional discussion. The case
where "the author(s) may not have regular [...] mailboxes"
begs the question of what appears in the mandatory From
field, which is supposed to list the author's (or authors')
mailbox(es). The example in RFC 822 A.2.6 uses the Sender's
mailbox with a different display name. That provides an obvious
way for an author to provide a recommended mailbox for
individual responses as well as providing a suggestion for
other responses; viz. the mailbox for individual responses can
simply be used in the From field (with a suitable display name
and/or parenthesized comments).
5, 6: these are handled as just described; the issue of an
individual mailbox is handled via the From field, the remaining
use is addressed via Reply-To.
3, 7: combine delegation and list. One implication may be that
the handling of responses is being delegated to a list (a list
expander, a named group, or simply a list of mailboxes).
Are there any circumstances where one might wish to delegate
individual responsibility yet suggest responses to a list?
Perhaps (case 3), but probably not in combination also with
an alternative individual mailbox for the originator. Even these
cases can be handled using the available originator fields:
Case 3:
From: (on behalf of, and delegating authority to)
J(_dot_)Doe(_at_)example(_dot_)com
Sender: (authored by) Boss(_at_)example(_dot_)com
Reply-To: The Committee: Tom(_at_)example(_dot_)com, Dick at example.com,
Harriet(_at_)example(_dot_)com;
Case 7:
From: (on behalf of, and delegating authority to)
J(_dot_)Doe(_at_)example(_dot_)com
Sender: (authored by Boss(_at_)example(_dot_)com while on vacation)
Room123(_at_)some-hotel(_dot_)net
Reply-To: The Committee: Tom(_at_)example(_dot_)com, Dick at example.com,
Harriet(_at_)example(_dot_)com;
Comments: If you value your job, don't bug me; general discussion
among the committee, call on J. Doe if necessary
The use of comments, display names (in the named group), and
Comments message header fields demonstrate how an author can
provide indication of why a suggestion has been made for
responses, and to give some guidance to prospective respondents
who might consider deviating from that suggestion. Body text
provides yet another mechanism.