a:
> Hello.
>
> I have mail server named "mx.example.com" that handles mail in
> "example.com" (virtual) domain. I use postfix 3.4.6 for this server.
> When something wrong happens, mail is dropped to postmaster with
> "double-bou...@mx.example.com" envelope sender and
> "mailer-dae...@mx.example.com" in the "From" header, which leads to
> SPF failure and spam filter triggering, because mx.example.com is not
> intended for using as ordinary mail domain.
That description is incorrect. A double-bounce means means that Postfix
could not send a delivery status notification. You need to fix that
problem first.
The double-bounce address is completed with $myhostname, to make
it valid for the machine from which it originates. If delivery of
that message fails it MUST BE DISCARDED, otherwise undeliverable
mail may keep looping indefinitely.
These messages should not be sent to a remote destination. If you
must send it offsite, use canonical maps; I take no responsibility
if your change causes bounces to keep looping between systems.
Wietse
