New message notification by email

[whym]

We would like to make sure the user notice messages they have received. In the Wikimedia Commons community, more often than not, missed talk page messages can cause trouble. (In the worst case, the user can be blocked for "ignoring warnings".)

We can ask the user to enter their email address so that we can let them receive notifications by email. I believe we can use https://www.mediawiki.org/wiki/API:Edit_-_Set_user_preferences and https://www.mediawiki.org/wiki/API:Options for this.

As a related enhancement, we also could have native notification. (but not strictly necessary if we have email) See also the issue on Echo integration (#7).

[janpio]

+1 on encouraging users to fill out their email address for email notifications.

Re "native" notifications, see #871

[misaochan]

Sounds like a good idea to me.