Exchange 2007 on Windows 2008 does not deliver mail to some domains

Exchange 2007 running on a Windows Server 2008 server does not properly deliver mail to certain domains.

Further testing finds that attempting to telnet to port 25 from the server to the remote domain provides a blank screen instead of providing the expected header.

Microsoft reports that this problem occurs because routers do not support the TCP autotuning settings in Windows Server 2008.

The resolution to this issue is to disable AutoTuning

Click Start, type the following in the Start Search box, and then press ENTER:
runas /user:Local_Computer_Name\administrator cmd

When you are prompted for the administrator account password, type the correct password, and then press ENTER.

Open a command prompt, type the following command, and then press ENTER:
netsh interface tcp set global autotuninglevel=disabled

This command disables the Receive Window Auto-Tuning feature.

Exit the Command Prompt window.

Restart the computer.