On 26 Apr 2017, at 20:41, Osman ÇAKMAR via Exim-users <exim-users@???> wrote: > The "F = <>" section is empty.
This is by design, and completely normal behaviour.
MTA software is usually configured in such a way that it will not respond to the null envelope sender “<>”. This prevents autoresponders autoresponding to autoresponders, or “autoresponder wars”.
Those of us who have been around email for a long time have seen these things happen for a variety of reasons, most of which revolve around poor decision making by the writer of a piece of software or the configuration for it.
If your gateway rejects all messages with a null envelope sender, how do you expect to accept bounces from external hosts?