[exim] Blocking dynamic IPs

Hi @all!

In order to reduce the daily quantity of trash in our system, we'd like to
block the E-Mails from dynamic IPs (of course, I mean, the E-Mail from MTA
with dynamic IPs! Not normal communication between a customer Mail-program and
our Servers!).
Has anyone already done it? How can I do it with Exim?
Additional question: how can I manage an "exception list" (for example of
Servers with dynamic IP but registered in DynDNS)?

Thanks a lot!
--
_______________________________
Luca Bertoncello
-Programmierung / Mailserver-

IMS Internet-Media-Service GmbH
Bärensteiner Straße 7
01277 Dresden

Fon: +49 351 2112034
Fax: +49 351 2112020
email: bertoncello@???