[Exim] Blocking forged messages

Hi,

Today I had some interesting mail, which I believe some of you had to deal
with before. The sender was marked <>, the returnpath was the same as
recipient. This is spam, trying to get it as a bounced message.

Next time this clown tries to post anything he will read a custom message,
so I have care of it, but I wonder if any of you have any suggestion how to
block these kind of mail.

Sender verification cannot be used because MAIL FROM: <> ( see also chapter
45.5 in spec doc), Reply-to and recipient are local users.

I think that it might be interesting to more people.

Regards,

Bart van Dommelen.