I've recently setup exchange and after a lot of configuring with my webhost and isp (and assitance on here) with the a records, mx records and reverse DNS lookup I have managed to finally get exchange successfully sending emails out.
However emails cannot be received. An external port check on 25 says that there is no route to host although the port is open on the router.
If I telnet on my exhange server (ruunning Server 2003 enterprise) I can only access the exchange server if I telnet the actual IP address of the server. If I telnet using mail.mydomain.com.au it says "Could not open connection to the host, on port 25: Connection failed".
When I do a nslookup on mail.mydomain.com.au I get:
Address: 192.168.2.8 (This is the internal IP for my SBS2003 server NOT my Exchange Server)
Address: x.x.x.x (My permenant IP as assigned by my ISP)