On Sun, 29 Aug 2004, wayne wrote:
The MTA being authorized is the sending MTA. Whether the
authorization is done by the receiving MTA or the receiving MUA is
irrelevant.
You're way wrong on this one. It can ONLY be done by receving MTA as
MUAs are not participant in SMTP session and only pickup email from
mailbox after the fact. MUAs have no reliable way to know identity
of SMTP server(s) previously involved in email transmission and can
not stop the tranmission and its only options are generally to discard
the email - they can't even bounce messages (bouncing is also part of SMTP
system; and not all MUAs have access to knowing envelope mail-from which
is required for proper bounce and while MUAs can return bad messages
through other means, by using Reply-To header and including bad message
as part of the reply in way similart to mail server generad bounce, they
are not supposed to pretend to be part of SMTP transmission).
--
William Leibzon
Elan Networks
william(_at_)elan(_dot_)net