Isaac,
I added per your instruction
<center>**PLEASE DO NOT REPLY TO THIS EMAIL. IT IS NOT MONITORED**</center><br><br>Hello %%USERNAME%%,
and I think it made a major difference, At least in theory.
I tested to send a PM to my other account and when reading the email it looked clear to me as email receiver that I should click on the link rather replying to the email.
Thanks!!!