[exim] help me close an open relay

Hello,

I am using exim 4.67 with mysql support enabled (vexim). Everything is
well but I must have made a mistake at some point and my exim can be used
as an open relay.

2007-05-29 11:44:10 1HsyFN-000Fr1-Uq <= <> H=mx.spamcops.de
(spamcop.kicks-ass.org) [87.106.79.226] P=smtp S=945
id=xMz8+BUjeZm/+8uwW6m2n6b8mo1ENicP@??? from <> for
listme@???

which results in

2007-05-29 11:44:11 1HsyFN-000Fr1-Uq => listme@???
R=dnslookup T=remote_smtp S=1002 H=spamcop.kicks-ass.org [87.177.228.9]
DT=1s

Can you suggest from your experience where to start troubleshooting? Is
this the case of a mistake in a router?

All other checks went fine - no relaying but with an empty envelope sender
yes it is possible.

I'd really appreciate your help!

Thank you in advance!

--
Zbigniew Szalbot