Greetings, I know email notification functionality in general is being discussed on other threads, but I wanted to talk about a very specific piece of it: the subject line.
Each message's subject line begins with: "[Atlassian Communty] "
Example: [Atlassian Community] New answer available in JIRA
Can you remove "[Atlassian Community] " in the subject line? The "FROM" value is "Atlassian Community" so there's no need to display it twice. Those 22 characters could be used to display more of the real subject line (which hopefully will one day be related to the question/discussion/article, rather than today's generic "New answer available..." copy.
Here's how this looks today in both a destop email client (Thunderbird 45.8 on a Win 10 machine) and on a smart phone (Samsung S7). A lot of wasted space is taken up by the beginning of the subject, especially on a mobile view.
Desktop View:

Mobile View:

Thanks for considering!