On Fri, Jul 14, 2023 at 04:30:03PM +0000, Brian Spraker via Exim-users wrote:
> Having a lot of new spam get through to the servers over the past few weeks.
> I am noticing in the Exim logs and also in the email headers that the "Return-Path" is empty.
> Is there a suitable way to block any emails that have empty return-paths and would this cause any other potential problems like mail failure notifications not getting through?
Blocking such messages violates RFC2821 p.4.5.5 ("Messages with a null
reverse-path"), similar for successors of RFC2821, resulting in loss of
non-delivery notifications and other kinds of automatic messages.
It also blocks popular sender verify callbacks, based on use of <>.
Mails from your users can be "misterically lost" due to a simple typo
in recipient's address!
But such blocking is practically no-op against spam.
Collect statistics if you don't belive.
--
Eugene Berdnikov
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