> On Apr 8, 2019, at 1:30 PM, Ntek, SIA Janis <i...@ntek.lv> wrote:
>
> I used
> root@othermail:~# mail -s test1 -a "From: us...@mydomain.tld"
> us...@mydomain.tld < /dev/null
>
> Which, judging by man mail, spoofs Header From,
True, but irrelevant, the actually relevant detail is that it also
sets the *envelope* sender address (which is a different thing from
any "Sender" header in the message). You don't appear to have
learned the difference between email message headers and the message
envelope. Find a good guide and read it.
> which was blocked with "reject_sender_login_mismatch",
That was the envelope sender, NOT the From header.
> as Viktor said my spam attacker used Header sender
No, your spam attacker used an envelope sender address,
distinct from the "From" header of the message, that did
not run afoul of your rules.
--
Viktor.
