Investigate email deliverability issues

[danieladugyan]

We've recently hade some issues with emails bouncing. Investigate which tools are available to us to mitigate against these issues. Here are some links to help you get started:

• https://www.gmail.com/postmaster/
• https://support.google.com/a/answer/81126?hl=en

[Tomas-Ka]

Mail for password resets are also broken again. Could this be a configuration error? Needs looking into

[danieladugyan]

Mail for password resets are also broken again. Could this be a configuration error? Needs looking into

That's unrelated to this issue. Instead, it's caused by #119.