At 10:34 PM 6/2/2002 +0200, Florian Weimer wrote:
Suppose a mail-based service needs to send an automatic reply to an
incoming mail message. Mail is received sent over a protocol which
contains an envelope sender (such as SMTP).
Should the service use the envelope or the header address to choose
the recipient for the automatic reply?
The important distinction is between a reply by the transport service,
about transmission, versus a reply by an email-based application, about an
activity of the application.
If the reply is about email transport, then the envelope address should be
used, per RFC 2821. If the reply is about the application-level service
that is simply using email as an underlying service, then the reply should
use the rules in RFC 2822:
3.6.2. Originator fields
...
The originator fields also provide the information required when replying
to a message. When the "Reply-To:" field is present, it indicates the
mailbox(es) to which the author of the message suggests that replies be
sent. In the absence of the "Reply-To:" field, replies SHOULD by default
be sent to the mailbox(es) specified in the "From:" field unless otherwise
specified by the person composing the reply.
and
3.6.3. Destination address fields
...
When a message is a reply to another message, the mailboxes of the authors
of the original message (the mailboxes in the "From:" field) or mailboxes
specified in the "Reply-To:" field (if it exists) MAY appear in the "To:"
field of the reply since these would normally be the primary recipients of
the reply.
...
Note: Some mail applications have automatic reply commands that include
the destination addresses of the original message in the destination
addresses of the reply. How those reply commands behave is implementation
dependent and is beyond the scope of this document. In particular, whether
or not to include the original destination addresses when the original
message had a "Reply-To:" field is not addressed here.
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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