Yesterday I installed a Cisco 800 series router on my network. (Widows Srver 2003 64 bit with Exchange 2007)We also got rid of all public IP's and are now using private ip address. In the configuration for the Cisco Router we translated all of the old external IP addresses to reflect the new private IP's. Everything works on the network except that we can't receive external emails. I have tried everything. Any help would be appreciated.

check the receive connector properties on the network tabverify that the local IP addresses are correct

Thanks jim, but can you be a little more specific? Is this is locatedthe exhange management console?

yes, under server configuration / hub transport

Yes, the local IP addresses are correct.

Also we use Relexions for spam filtering. When I log into Reflexions I don't see any emails at all and I have sent multiple test emails from my gmail account.

One more thing.....if our domain went from being connected directly to the internet to now being NAT'ed, will I have to change the A, MX records, etc??

your mx and a records should be your internet facing ip address (most likely unchanged)is your relexions system between the internet and your hub transport server? it sounds like your receive connector should be updated with the new ip address of this system.

Check info: 1. Please describe the detailed exchange topology 2. Please check if theres any NDR in the Gmail mailbox? 3. Please try to perform a Telnet test 4. When the symptom recurred, please use this website to test the mail flow. And also, please use Mail Flow Troubleshooter, see if we can get any related information 5. We can also enable SMTP protocol logging on the receive connector, and monitor the issue

An additional test to Jame's response... Run "Inbound SMTP Email Test" @https://www.testexchangeconnectivity.com/and check the result and resolution links... Amit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com