Hi Rainer,
Rainer Dorsch <ml@???> (Sa 12 Dez 2015 19:50:32 CET):
(…)
> I looked to the latest message I received:
>
> Event though it reports an empty sender
>
> 2015-12-12 19:38:36 1a7p3y-0006e9-TJ <= <> H=(69.17.215.194) [69.17.215.194] P=smtp S=2719
> 2015-12-12 19:38:36 1a7p3y-0006e9-TJ => rd <metzingen@bokomoko(at)de> R=local_user T=maildir_home
>
> the full header contains a non-empty From: line:
> From: evseev@???[1]
The From: header is in no way related to the message's sender. Despite
that they carry the same value often.
The "sender" means the SMTP protocol sender (that is, the value of the
"MAIL FROM" command, (RFC (8|28|53)21), the From: Header is just part of the message that
is being transferred (RFC (8|28|53)22).
Because a "Sender:" message header might exist as well, I often use the terms "Envelope-From", or
"Envelope-Sender" (both being the same) in contraast to "From:"- or "Sender:"-Header.
> Is the empty sender referring to a part of the SMTP protocol and therefore this is not a
> contradiction?
Exactly.
Bounces have an empty envelope sender (<>), because automatically
sending errors reports in response to error reports isn't useful. But
bounces may carry a completly valid From: (or Reply-To: or Sender:)
line. The From:/Reply-To: should be honoured by a MUA responding to some
bounce. Therefore this should be the account of a person taking care
about the sending system (often postmaster@???).
But as always, it's my understanding of what's going on, it might be
completly wrong.
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann
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