On 21.10.16 17:41, Paweł Grzesik wrote: > So here we have DATA where I can type From:, To: and Subject: then > message and e-mail will go from the "From:" instead of the one from > the header "MAIL FROM:".
No. Postfix - the MTA - uses the envelope sender address (which you can verify on the receiving server). Mail clients - MUA - display the "From:" Header content, which can be completely different. This is just how E-Mail works. Don't try to block it, it makes no sense to do so. You'll definitely want to read up on this subject elsewhere, because this is not Postfix specific. -Ralph
