Hi,
68.160.79.3 is not listed when I check your database, but my domain is still getting blocked and I get a lot of bounce backs from your reporting service. MX and PTR records check out fine. I don't have open relays since the last time I checked and I'm using TrendMicro IMSS for email gateway. Cisco firewall is hardened to the only port 25 for this IP. I have also turned off NDR's and and Out Of Office replies to the internet from going out.
Heck, I have even ran a full fledged AV scan on all nodes inside my network and they turn up clean.
I'm going nuts here, what else am I missing?