I wanted to suggest a change in the emails, they are (sorry if it sounds agressive) unreadable.
Could you add items like: on which project the issue was written (I have a lot of repos, and I don't always click on the link immidiatly if an issue is written) add a little description, the mail is too concrete: for example instad of
<USER>: <issue details>
<USER> has written: <issue details>
and so on.
- another idea would be to add styled emails. I'm a developper, so I know what blank text is, but my coworkers are community managers, they don't :-)