[Exim] filter out mails with empty from ? how?

Hi!

I still have the problem with my acl.
I use
accept hosts = :

And I think this even accept ALL bounces and all messages withj an
empty from: field.
But I get fake-bounces with an empty from field and a non existent
receiver.
These messages got frozen.I want them to get dropped.
Is my guess right that the above rule accepts all mails with an empty
from: field?
And if I delete the above rule, I don´t know exactely which mails will
fail. Does anyone know which services sends email to exim with local
smtp transports?`

Cya
Lars