Replying to an email notification breaks if a quote from the notification is included. Anything past the quote is not included.
For example, take this notification:
Example notification where I talk about something really interesting.
Second paragraph where I start going on about that really interesting thing.
Now I’m just ranting…
So, in reply, I want to include a quote from that email. If I do the following, the email is rejected as having no content:
<quote> <my post>
… the following results in just
<my post> being added - the quote nor the additional parts are added:
<my post> <quote> <additional part of my post>
So, basically, processing email replies ‘stops’ at the quote, and doesn’t continue processing. This breaks replies where a quote starts off the reply, since the processing stops straight away.