Hi @Andrew_M ,
I think instead of clicking on a link within the body text they can simply hit the Reply or Reply All button on the original email with a short note saying "Done"
This will do all that you need.
i. sends a message back to me
ii. plus close the email that had the link
iii. so they can see that the automated message has been sent due to the message being closed
- The message can be viewed in their Sent box.