Ok, I did a little bit of searching:
For the envelope FROM, RFC-1123 specifies that the mail server making
"final delivery" of a message:
MUST pass the MAIL FROM: address from the SMTP envelope
with the message, for use if an error notification message must
be sent later
...
IMPLEMENTATION:
The MAIL FROM: information may be passed as a parameter or
in a Return-Path: line inserted at the beginning of the
message.
...
The syntax shown for the Return-path line omits the possibility
of a null return path, which is used to prevent looping of
error notifications (see Section 5.3.3). The complete syntax
is:
return = "Return-path" ":" route-addr
/ "Return-path" ":" "<" ">"
So, for envelope from checking, we should use the "Return-Path" header.
I'll make a rule which compares Return-Path to From: and see how it does
at differentiating spam from nonspam.
For the envelope TO, there seem to be 2 "standards", depending on when
the info is added to the message header. One is added on SMTP-reception
(such as with exim I think), in which case the header used is
"Envelope-To". The other is added during delivery, after local alias
resolution, etc, and is called "Delivered-To" -- qmail does this, and
it's basically what Charlie is doing too. I think what we really want
to do for spam-id purposes is to compare the "RCPT TO:" info from SMTP
to the "To:"/"Cc:" fields in the message header. If you compare To/Cc
to the delivery address, then you'll think messages To:
[EMAIL PROTECTED] are spam (assuming that postmaster is an alias for a
real user), because the delivery-to will be [EMAIL PROTECTED] not
[EMAIL PROTECTED], which will be the envelope-to value.
So, Charlie, I would suggest altering your mail system to insert a
Envelope-To instead of X-Delivery-To (or at least standardize and use
Delivery-To). I'll implement Charlie's patch below but using
Envelope-To and add it to the SA distro. Then people can just make sure
their mail system adds the right header, and they'll automatically get
this feature.
C
dman wrote once:
>On Fri, Feb 15, 2002 at 02:52:05PM +0000, Nigel Metheringham wrote:
>| On Fri, 2002-02-15 at 14:45, dman wrote:
>| > On Fri, Feb 15, 2002 at 10:37:46AM +0000, Nigel Metheringham wrote:
>| > | In terms of headers, Return-Path: would be the one to go for.
>| >
>| > Well, in your message that I'm replying to, there is no
Return-Path:
>| > header. Maybe procmail sticks that in or something (I'm not using
>| > procmail), but I don't know where it comes from.
>|
>| Return-path: is added by the MTA on final delivery. For exim its a
>| transport option,
>
>Ahh, got it now. Return-Path: and Envelope-To: headers are just as
>good to me as a command line option. Either way the site's admin has
>to set up the MTA properly to deliver the info.
On Sun, 2002-02-17 at 13:12, Charlie Watts wrote:
> sub check_if_listed_recipient {
> my ($self) = @_;
> my $deliveredto = $self->get ('X-Delivered-To:addr');
> my $to = $self->get ('To');
> my $cc = $self->get ('Cc');
>
> if ($deliveredto eq '') { return 0; }
> if (($to =~ /${deliveredto}/i) || ($cc =~ /${deliveredto}/i)) { return 0; }
> return 1;
> }
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