A single user is not receiving email notifications.
They get notifications in system (the bell icon), they get emailed by the system when I log in as them (so correct email is set up), I've checked their user settings to make sure they haven't turned off email notifications, and the notification scheme of the project doesn't have any specifics that would stop this one user from getting notifications (reporter assignee and watcher all set as getting emails).
We set up a test ticket in the project to test, assigned and commented etc and nothing.
I've seen a couple of other tickets opened here around similar, and have followed the routes suggested in those (check spam and filters etc), the user is on gmail so shouldn't have any issues there. No one else in the organisation (some 1000 users) are having similar issues.
Notification helper shows they should be getting notifications emailed.
Despite having plenty of experience dealing with this sort of thing I am stumped as to why this might be happening!
-Not Notification Scheme
-Not user account personal preferences
-Not Spam/Filtered
-Not email
-Proper Stumped