Proper support for email notification templates
This is the umbrella issue for supporting templates for email notifications. A lot of the existing broken code is legacy from MM2.1. Because of the split between Postorius and Core, we can no longer assume there is any url to click on. The default templates will be very simple and explain how to interact with the system via email.
I am currently working on a branch that will fix this the way I've described often on the mailing list.