On 2024/12/26 22:15, Wietse Venema via Postfix-users wrote:
Cowbay via Postfix-users:
Postfix adds a missing (Resent) Message-ID, Date, or From header
when a message is received as an original or resent submission, not
when it receives a message from a remote MTA (for some definition
of 'remote').
(Postfix detects that a message is resent when it contains a Resent-
header, including Resent-From, Resent-Message-Id, Resent-To,
Resent-Cc, Resent-Bcc, Resent-Reply-To, or Resent-Sender).
Okay. In my situation the mail should be from remote MTA (from port 25).
And since Postfix detected the Resent-Sender, then it adds the missing Resent-
headers.
Postfix is not supposed to add or rewrite headers with mail from
remote MTAs, because doing so could break DKIM signatures.
This lets me know that I should remove the local_header_rewrite_clients
parameter or just set as permit_inet_interfaces.
If you use a content_filter or smtpd_proxy_filter then the after-filter
Postfix sees a connedtion from localhost and needs to be told that
this is not a local submission.
COuld that be the problem?
No, I don't have problems.
The Postfix Resent- implementation is based on RFC 822 which in
section 4.1 syntax appears to suggest that 'originator' (From:,
Sender:) come before before 'resent' (Resent-From:, Resent-Sender).
Also, in RFC 822 the interpretation of multiple "Resent-" fields
of the same type was explicitly undefined. There were no multiple
Resent- blocks, let alone whether a newer Resent- block precedes
or follows an older one.
Thus, the Postfix implementation supports one Resent- block, and
its placement meets RFC 822 requirements.
(The implementation was done at a time that prepending would have
been technically impossible, because Postfix reads and writes out
headers one by one, and it would not have been able to prepend
something to a header that it had already written out.)
So yeah, you can blame me for not parsing RFC 5322 for changes
in Resent handling.
I post this issue just in case Postfix has unknown bugs. Now I
know that it's by design.
And actually I have no email clients that could send Resent- mails.
There is a feature "Redirect" in Thunderbird but the redirected
mails have new Date and To headers without any Resent- header, so
it's not Resent-.
Considering that RFC 5322 made a complex mess of Resent- headers,
it seems best for Postfix to stop adding "missing" Resent- headers
by default.
Wietse
Since the Resent- headers is not necessary Postfix's responsibility and the
usages of the Resent- headers are rare, it appears fine to me to stop this
feature.
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