Jeremy Harris via Exim-users wrote on 14-05-24 00:04:
On 13/05/2024 17:02, Anton via Exim-users wrote:
Accordingly to the Googles' recent changes
https://support.google.com/a/answer/81126?visit_id=638483404863497961-2571982079
https://support.google.com/a/answer/175365?hl=en&ref_topic=1354753
messages forwarded to Gmail should contain X-Forwarded-For: or X-Forwarded-To:
headers.
What is the best way to add them?
My problem is that I'm aware a message is forwarded only at the routers level
(the final destination e-address is taken from /etc/aliases or ~/.forward)
and :at_start: option does not seems to work in transports:
the directive
headers_add = :at_start:X-Forwarded-For: $acl_m_For
adds the header in the main block and not in the beginning, which makes it
useless.
The second page you refer to does not specify a position a position in
the headers where an X-Forwarded-For: header should be added.
Your term "in the main block" is not common usage, so I am uncertain as to your
thinking.
Sorry, I don't know the right terms. What I called the "main block" is the set
of To: From: Date: Message-ID: and alike headers
versus the "flow" of Received: Authentication-Results: etc. headers added at
each hop during message transit.
Do you have specific reason to think that the position that Exim's transports
place a header when specified by a transport or router option (not "directive")
is not useful?
Since a mail can be forwarded several times before reaching its final
destination, it looks logical to put X-Forwarded header(s) at each hop [where
it was forwarded].
Here is how the headers looks when Google forwards a mail themselves:
Received: from google.com by final.destination
X-Forwarded-To: final@address
X-Forwarded-For: initial.addr...@gmail.com
Received: from first.MTA by mx.google.com
Received: from MUA by first.MTA
To: initial.addr...@gmail.com
Message-ID: xxx
(mixed with different DKIM/ARC/Authentication-Results headers at each hop).
This comportment could be reached by supporting ":at_start:" option in
routers/transports headers_add.
Thank you Jeremy for your answer.
A.
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