Oliver Sommer 
2008-12-22
After Migration of EBS Security Server to new Hardware or migration to a new virtual Machine (VM) or any other scenario where the network adapters of the security server have been changed you might experience that Exchange is uncapable of sending outbound Email although incoming Mailflow is working just fine.
In my case this happend because during Migration of the security server the new VM became new virtual NICs (network interface cards). Those have been bound to the OS in the wrong order, so that the external Network adapter has been first and the internal one last.
To change that open the "Network and Sharing center" and open the network connections as shown below:
Then open the advanced settings as show above and resort the binding order to have the internal NIC on top as shown below:
In addition the DNS registration has been enabled at the external NIC, so that this adapters external IP adress has been registered in DNS as the IP of the security server.
You need to uncheck that register to DNS setting at the external NICs TCP/IP v4 properties and enable it at the internal one:
