--On 3 August 2006 18:33:08 +0100 Chris Lightfoot <chris@???>
wrote:
>
> If an SMTP server has accepted the task of relaying the mail and
> later finds that the destination is incorrect or that the mail cannot
> be delivered for some other reason, then it MUST construct an
> "undeliverable mail" notification message and send it to the
> originator of the undeliverable mail (as indicated by the reverse-
> path).
In which case, the matter hinges on whether the return path can contain
more than one address. If it does, the bounce generator can't reasonably be
expected to pick between them. Indeed, if the only reason to put two
addresses in there is that both addresses want the bounces. However, the
answer is that the return path can't contain more than one email address.
RFC 2821, section "4.4 Trace Information" says
"The primary purpose of the Return-path is to designate the address to
which
messages indicating non-delivery or other mail system failures
are to be sent. For this to be unambiguous, exactly one return path
SHOULD be present when the message is delivered. Systems using RFC
822 syntax with non-SMTP transports SHOULD designate an unambiguous
address, associated with the transport envelope, to which error
reports (e.g., non-delivery messages) should be sent."
4.1.1.2 MAIL (MAIL) says:
..."The reverse-path consists of the sender mailbox. Historically, that
mailbox might optionally have been preceded by a list of hosts, but
that behavior is now deprecated (see appendix C)."...
"Syntax:
"MAIL FROM:" ("<>" / Reverse-Path)
[SP Mail-parameters] CRLF"...
The syntax is further expanded as:
Reverse-path = Path
...
Path = "<" [ A-d-l ":" ] Mailbox ">"
A-d-l = At-domain *( "," A-d-l )
; Note that this form, the so-called "source route",
; MUST BE accepted, SHOULD NOT be generated, and SHOULD be
; ignored.
Mailbox = Local-part "@" Domain
Further, there are many many references in rfc2821 to the (singular) return
address.
--
Ian Eiloart
IT Services, University of Sussex
