[exim] Change filename in MIME ACL?

I've received a complaint about the MIME filename filtering I use.
Apparently Netscape forwards mail as a message/rfc822 attachment with
the original Subject: header as the filename. And when that subject was
"Your order from Amazon.com" it gets rejected for being an executable.

I'd like to be able to change the filename (or even just drop it) in the
MIME ACL.

Also, I don't see an obvious replacement for $demime_errorlevel in the
new MIME stuff. Is there one?

--
dwmw2