[Exim] how to verify recipient on a mailhub

Hello,

exim receices all mail comming from the internet and after virusscanning,
... forwards
it to an lotus domino server;

recently i get *tons* of faked emails (sender claims to be from our domain,
recipient is
combination of chars and numbers in localpart, for example:
4edre57887@???)

my question is:
how can i configure exim to do a recipient verification on the relay host
for all
incomming messages ?

parts of the config:
routers:

smart_relay:
        driver = manualroute
        domains = +local_domains
        transport = remote_smtp
        route_list = * horn.intern.ebewe.at

Thanks in advance
Wolfgang Fürtbauer
----------------------------------------------------------------------
Wolfgang Fuertbauer (E-Mail: Wolfgang.Fuertbauer@???)
EBEWE Pharma                          Tel: ++43 7665 8123 315
Mondseestrasse 11                     Fax: ++43 7665 8123 11
4866  Unterach, Austria
http://www.ebewe.com