XIMS: How to Disable Support for ETRN (258292)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SUMMARY

Exchange Server supports the use of a Simple Mail Transfer Protocol (SMTP) extension called ETRN for dial-up connections that use Remote Access Service (RAS). After the client host submits the ETRN command to the server host, a new connection is established from the server host to the client host, and mail to the client host domain is retried immediately.

MORE INFORMATION

You can disable ETRN by modifying the registry:

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

Using RegEdit

Start Regedit.exe.
Locate the following key in the registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIMC\Parameters
Click Edit, and then click New DWORD Value.
Type DisableETRN. Under Value data, type 1.

Using RegEdt32

Start Registry Editor (Regedt32.exe).
Locate the following key in the registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIMC\Parameters
On the Edit menu, click Add Value, and then add the following registry value:
Value Name: DisableETRN
Data Type: REG_DWORD
Value: 1
Quit Registry Editor.

For more information about how to use ETRN, see Microsoft Exchange Server Concepts and Planning, and Request for Comments (RFC) 1985, "SMTP Service Extension for Remote Message Queue Starting."