[exim] ACL messages are scattering my mainlog

Hello,

I have an ACL in my exim setup, that uses greylisting for each
IP-address that connects to it. It is generally interesting to see the
connection attempts, but I would be satisfied if I wouldn't have to see
it once in mainlog and once in rejectlog.

How can tell exim to send the messages about a certain ACL only to
rejectlog and _not_ to mainlog?

Regards
Marten