On Sat Sep 12, 2026 at 1:45 AM CEST, Thomas Bohl wrote:
Ignoring the filter discussion, isn't mask-src on the submission port
enough (to avoid exposing internal details)? I use it for the exact purpose.
Speaking of which, maybe it'd make sense to reimplement it in a similar
was as Postfix does, which apparently is more compatible and strictly
standards compliant? [1]
OpenSMTPD's mask-src does this:
Received:
by mesiano (OpenSMTPD) with ESMTPA id c9aca955
for <[email protected]>;
Sat, 12 Sep 2026 00:13:35 +0000 (UTC)
While Postfix's smtpd_hide_client_session does this instead:
Received: by mail.pappacoda.it (Postfix) id ABBB223545
for <[email protected]>; Sat, 12 Sep 2026 02:13:35 +0200 (CEST)
i.e. smtpd drops the "from" line entirely, leaving a blank line instead,
while postfix also stops saying "with ESMTPA" in the "by" line (and does
not leave any blank line behind).
[1]: "The redacted form hides that a message was received with SMTP, and
therefore it does not need to provide the FROM clause according to RFC
5321 section 4.4. The redacted form still meets RFC 5322 requirements.",
https://www.postfix.org/postconf.5.html#smtpd_hide_client_session
