XF 1.5 Editing conversation notification emails

I would like to edit the notification emails sent out for conversations. Specifically, I want to move the "Please do not reply ..." stuff to the top of the email, and make it larger and bolder to be sure it's read. I've added html tags to make the text bolder, but I've been unable to locate the tempate that controls these email messages to move the text to the location I want. Can anybody point me in the right direction?