Configure the Tarpitting Interval

Configure the Tarpitting Interval

You can configure the Receive connectors that process inbound messages from the Internet to slow down the Simple Mail Transfer Protocol (SMTP) response. Make sure that you enable tarpitting functionality on the Receive connectors, especially if you have enabled the Recipient Lookup feature of recipient filtering. If you do not enable tarpitting, and you have enabled the Recipient Lookup feature, you are exposing your organization to a directory harvest attack. A directory harvest attack will likely cause more spam.

When you specify a tarpitting interval time on a Receive connector, tarpitting is enabled. The default value is 5 seconds. We recommend that you start with a value of 5 (seconds). Use caution if you decide to change this value. An overly long interval could disrupt ordinary mail flow, whereas an overly brief interval may not be as effective in thwarting a directory harvest attack. If you change the tarpitting interval value, do so in small increments.

You set the tarpitting interval on the Security tab of the Receive connector property pages in the Exchange Management Console, or alternatively, you can also set the tarpitting interval by using the Set-ReceiveConnector command in the Exchange Management Shell.