At 01:52 AM 6/3/2002 -0400, Keith Moore wrote:
For example, automatically generated message disposition notifications aren't
generated by the mail transport system - they're generated by the recipient's
right. meant to cover all "transport-related" communications.
my main intent was to distinguish application-level replies from
"handling-related" replies.
If the sender is a human, and he/she is expecting
an automatically-generated reply,
the responding software cannot know what the originator -- human or
otherwise -- is expecting, except as indicated by the presence or absence
of a Reply-to field.
On the other hand, if the
sender is not expecting an automatically generated reply, but is expecting
a reply from a human (as in a "out of the office" response) then sending
to the return-path address usually makes more sense.
no.
Consider a message
intended for a mailing list where the sender specified the list address in
the reply-to field (which is a perfectly reasonable thing to do) - if a robot
answers the mail on behalf of a list recipient and sends the reply to the
entire list, this will be seen as disruptive.
it is frankly just as bad to have it go to the message originator. not as
bad in scale but as bad in inappropriateness.
in pretty much all cases of that type of situation, the fact that the
recipient is not explicitly mentioned in the To or CC field means that the
software should not send a reply at all.
(Aren't we all a little tired of getting vacation notices from mailing list
recipients' automata? We did not send our message to that person
specifically, so getting a vacation notice from then is wildly inappropriate.)
And if both the sender and recipients are computer programs - i.e. if
this is the use of email within an application - it's probably best for
the sender to never use reply-to (and for the recipient to ignore it).
Reply-to overrides From. There is no reason not to use it.
The bottom line is that the specifications leave a lot of wiggle room
regarding use of Reply-To because we really haven't been able to find
a clear set of rules that works for all cases.
They do not leave as much wiggle room as folks often want to believe. The
protocol intent of Reply-To was and is simple and precise. The exact
boundary of its use, relative to use of an envelope-type address, has moved
a bit, but not much.
Most of the problems with Reply-to are a) its semantics getting overloaded
by lack of another field for mailing list automata, and b) a tendency for
folk to forget that we are just talking about a protocol, albeit one that
often has a human as part of the protocol engine.
d/
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Dave Crocker <mailto:dcrocker(_at_)brandenburg(_dot_)com>
Brandenburg InternetWorking <http://www.brandenburg.com>
tel +1.408.246.8253; fax +1.408.850.1850