[Exim] exim 3.2 returning attachments after a non-delivery

hi there

we still use exim 3.2.

How do I find out, what exim does with a rejected email (incl.
attachment) exactly.

Does it returns the whole attachment? or doesn't it? The only thing I
could find out in the config-file was the limitation of the return-size
of an email (10K). Or an other thing I did is sending an email with an
attachment, to see that the email is returned incl. attachment. But I
could not find the config in the config-file.....

Has anybody an idea/tip where to look?

thanks
bh