Stefan F?rster:
> When I submit a mail to my Postfix server (using SASL auth over a TLS
> connection), Postfix adds the following received header:
>
> Received: from aletheia.cite.lan (33.33.33.333.dynamic.cablesurf.de
> [33.33.33.333]) (using TLSv1 with cipher ADH-AES256-SHA (256/256
> bits))
> (No client certificate requested) by mail.incertum.net (Postfix) with
> ESMTPSA for <c...@example.net>; Fri, 31 Jul 2009 23:42:33 +0200 (CEST)
>
> This is working as expected. If I create a new mail and forcibly
> insert the above header before I submit it, I get a NDR saying that
> there is a mail forwarding loop for c...@example.net - which is
As documented, Postfix uses Delivered-To: headers for loop detection.
Local delivery agent:
=====================
prepend_delivered_header (default: command, file, forward)
The message delivery contexts where the Postfix local(8) delivery agent
prepends a Delivered-To: message header with the address that the mail
was delivered to. This information is used for mail delivery loop
detection.
By default, the Postfix local delivery agent prepends a Delivered-To:
header when forwarding mail and when delivering to file (mailbox) and
command. Turning off the Delivered-To: header when forwarding mail is
not recommended.
Specify zero or more of forward, file, or command.
Example:
prepend_delivered_header = forward
Pipe delivery agent:
====================
flags=BDFORXhqu.> (optional)
Optional message processing flags. By default, a message is
copied unchanged.
...
D Prepend a "Delivered-To: recipient" message header with
the envelope recipient address. Note: for this to work,
the transport_destination_recipient_limit must be 1 (see
SINGLE-RECIPIENT DELIVERY above for details).
The D flag also enforces loop detection (Postfix 2.5 and
later): if a message already contains a Delivered-To:
header with the same recipient address, then the message
is returned as undeliverable. The address comparison is
case insensitive.
Wietse
> exactly what I expected, but I'm not 100% sure how this mechanism
> works. So my question is:
>
> Does Postfix compare both the sending host _and_ the recipient address
> in "Received:" headers? If not, with regard to "Received:" headers,
> which (if any) information is compared to detect a mail forwarding
> loop?
>
>
> Cheers
> Stefan
>
>
