How to Set the Sender Reputation Level Block Threshold

Exchange 2007

Microsoft Exchange Server 2007 will reach end of support on April 11, 2017. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.


Applies to: Exchange Server 2007, Exchange Server 2007 SP1, Exchange Server 2007 SP2, Exchange Server 2007 SP3

Topic Last Modified: 2006-09-18

This topic explains how to use the Exchange Management Console or the Exchange Management Shell to configure the sender reputation level (SRL) block threshold. Sender reputation is anti-spam functionality that blocks messages according to the characteristics of the sender. The SRL is a number between 0 and 9 that predicts the probability that a specific sender is a spammer or malicious sender. A value of 0 indicates that the message is not likely to be spam. A value of 9 indicates that a message is likely to be spam.

You can configure the threshold for sender blocking by SRL. This SRL block threshold defines the SRL value that must be exceeded for sender reputation to block a sender. By default, the SRL threshold value is 7. Use caution when you set the SRL threshold. A threshold that is too low may unintentionally block legitimate senders. A threshold that is too high may not block malicious senders or spammers. If a message is equal to or greater than the SRL block threshold, that sender will be added to the IP Block list from 0 to 48 hours. The default is 24 hours.

You can set the number of hours to be added to the IP Block list to 0 to monitor sender reputation without disrupting mail flow.

You should monitor the effectiveness of the agent at the default level and then adjust the value to meet the needs of your organization. For more information about how to adjust anti-spam configurations so that they work together to reduce spam, see Anti-Spam and Antivirus Functionality.

To perform the following procedures on a computer that has the Edge Transport server role installed, you must log on by using an account that is a member of the local Administrators group on that computer.

Also, before you perform these procedures, confirm the following:

  1. Open the Exchange Management Console on the Edge Transport server.

  2. In the console tree, click Edge Transport.

  3. In the work pane, click the Anti-spam tab, and then select Sender Reputation.

  4. In the action pane, click Properties, and then select the Action tab.

  5. Drag the Sender Reputation Level Block Threshold slider to the desired threshold.

  6. Under Threshold Action, click the Up or Down arrows on the When the sender reputation block threshold is exceeded, add the sender to the IP Block list for the following duration (hours) box to set the number of hours that the sender remains on the IP Block list.

  7. Click OK to save your changes and close the dialog box, or click Apply to save your changes without closing the dialog box.

  • To configure the SRL block threshold, run the following command:

    Set-SenderReputationConfig -SrlBlockThreshold <Int32> -SenderBlockingPeriod <Int32>

    For example, to configure the SRL block with a threshold of 6 and a duration of 36 hours, run the following command:

    Set-SenderReputationConfig -SrlBlockThreshold 6 -SenderBlockingPeriod 36

For detailed syntax and parameter information, see Set-SenderReputationConfig.