A. In the delivery properties > advanced, edit the proof properties and define a JavaScript block to calculate the current timestamp
B. In the delivery properties > advanced, edit the proof properties to append the current date time stamp when sending the proof
C. While sending proofs, manually change the subject line to include the current date time
D. Code the email delivery to dynamically append the date time in the subject line if a proof is being sent
Explanation:
Reference: https://docs.adobe.com/content/help/en/campaign-classic/using/sending-messages/key-steps- when-creating-a-delivery/steps-validating-the-delivery.html