How to Create an Outbound SMTP Filter List

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This article explains how to create IPSec filter lists for the purpose of blocking inbound and outbound SMTP traffic on TCP port 25.

Before You Begin

The procedure in this article specifies naming conventions in bold italic. As you work through the other related procedures as listed in How to Create a Block TCP 25 IPSec Policy, notice that the policies, descriptions, and filters that are named in earlier procedures are referenced in subsequent procedures (again in bold italic).

It is recommended that you review Slowing and Stopping E-mail Viruses in Exchange Server 2003: Optional Configurations before implementing this procedure.

Procedure

To create the outbound SMTP filter list

  1. In Group Policy Object Editor, expand Computer Configuration, expand Windows Settings, and then expand Security Settings.

  2. Right-click IP Security Policies on Active Directory, and then select Manage IP Filter lists and filter actions. The Manage IP filter lists and filter actions property page is displayed.

  3. On the Manage IP Filter Lists tab, click Add. The IP Filter List page is displayed.

  4. In the Name field, enter Outbound TCP 25. In the Description field, enter This filter responds to outbound requests on TCP 25, and then click Add.

  5. On the IP Filter Wizard Welcome page, click Next.

  6. On the IP Filter Description and Mirrored property page, enter a filter description, and then click Next.

    Note

    If you do not enter a description here, future troubleshooting with the Network Diagnostics tool (netdiag.exe) will not display the name of the filter.

  7. On the IP Traffic Source page, select My IP Address and then click Next.

  8. On the IP Traffic Destination page, select Any IP Address and then click Next.

  9. On the IP Protocol Type page, select TCP and then click Next.

  10. On the IP Protocol Port page, select From any port and To this port, and then enter 25 in the open field. Click Next.

  11. On the finish page, click Finish. On the IP Filter List page, click OK.

For More Information

For more information, see How to Create an Inbound SMTP Filter List.