mynetworks and postfix config questions

[Alex]

Hi,
I have amavis set up with postfix and spamassassin to relay mail for a
few domains after it is scanned to its final destination. Outbound
mail for these domains are processed by another system. This is only
for inbound mail. The server itself is not in one of the domains for
which it is relaying mail.

I've read quite a bit about how my setup should be configured, but I'm
still receiving messages like "Open relay? Nonlocal recips but not
originating: gene.conklin at mydomain.com".

I've set up @mynetworks to include the networks that amavis should
consider trusted. I have @local_domains_map set with only
".$mydomain".

Should @local_domains_map also contain the domains for which it relays
mail? It was unclear to me from the reading I did. It sounded more
like it should be used for the client domains that would be
connecting.

I have "-o smtp_send_xforward_command=yes" set in postfix, and
relay_domains contains the domains for which it should relay mail.

I'm not sure what other information I should provide to help troubleshoot this.
Any ideas greatly appreciated.
Thanks,
Alex