Preparing Windows Servers for the Upgrade › Configure SMTP Relay Restrictions

Configure SMTP Relay Restrictions

You can control mail relays to the IIS Simple Mail Transport Protocol (SMTP) virtual server for tighter security. When the SMTP virtual server is openly accessible, a user can distribute unwanted email through it.

Configure SMTP virtual server relay restrictions to allow access only to 127.0.0.1 and to disallow all other computers. The restrictions allow only selected computers to relay messages through the SMTP virtual server. Other computers cannot relay messages to the SMTP virtual server even when they meet the requirements set in the Authentication dialog.

Follow these steps:

1. Log in to the server as an administrator.
2. Install the SMTP Server feature.
3. Navigate to Administrative Tools and double-click Internet Information Services (IIS) 6.0 Manager.

   The Internet Information Services (IIS) 6.0 Manager window opens.

4. Expand your server name in the Console tree on the left.

   The server details are expanded. The SMTP Virtual Server appears under your server.

   Note: If the SMTP Virtual Server is not visible, add the SMTP server feature.

5. Right-click Default SMTP Virtual Server and click Properties.

   The Default SMTP Virtual Server Properties dialog opens.

6. Click the Access tab, then click Relay.

   The Relay Restrictions dialog opens.

7. Click Add.

   The Computer dialog opens.

8. Specify the following settings:
   • Select Single computer.
   • IP address: Enter 127.0.0.1.
9. Click OK.

   The Relay Restrictions dialog shows 127.0.0.1 in the Computers list. The computer with the IP address 127.0.0.1 has the status of "Granted" in the Access column.

10. Specify the following relay restrictions options:
    • "Only the list below:" Selected. This option allows only the computers in the Computers list to relay messages through the SMTP virtual server.
    • "Allow all computers which successfully authenticate to relay, regardless of the list above" check box: Cleared.
11. Click OK.

    The SMTP Virtual Server Properties dialog opens. With the options you chose, only the listed computers can relay messages through the SMTP virtual server. Unlisted computers cannot relay messages to the SMTP virtual server even if they meet the requirements set in the Authentication dialog.

12. Click OK.

    The SMTP Virtual Server Properties dialog closes.

13. Select File, Exit in the Internet Information Services (IIS) 6.0 Manager window.