SBS 2008 + Exchange 2007 - Strange Issue

[TrekCaptainUSA]

I've run into a strange issue on-site, with revolves around SBS 2008 with exchange 2007 running.

The exchange system isnt receiving mail from any external sources, such as google, Yahoo, or other systems. Internet is still operational, and the server is able to send and receive internal messages throughout the local net.

Was on the tech support chat for here, ended up checking all the server logs, exchange logs, and everything in event viewer, didnt find anything suggesting it couldnt get any data to it, and past that, there wasnt anything more suggested by the techs on the chat.

Sent 4 test messages from google, none even hit the server, so nothing was delivered. Any suggestions as to what to do next? Done a cold restart, as well as checked firewall and DNS settings, everything seems to work. :/