Perform an action only on the the first email in a email conversation

Scenario: You want to create an action, such as an alert, only when someone sends the first email in a email conversation/thread. However, you DO NOT want to perform that action when someone replies to the initial email.

Scriptlet: You can use an Exchange Transport Rule to detect the first email in a email conversation when the email initiated from within Exchange. Here is the Transport Rule code that will alert another recipient (specifically a page to my cell phone) when someone emails a specific email address. We will use Regex to detect the 32 character value in the Thread-Index header that ends with “==”, which identifies the first email in a conversation thread.

New-TransportRule -name “Perform_Action_On_First_Email” -Enabled $true -HeaderMatchesMessageHeader “Thread-Index” -HeaderMatchesPatterns “^.{30}==$” -RecipientAddressContainsWords servicedesk@domain.com -blindcopyto Page-Steves-Phone@domain.com