While I've seen others with similar issues here, I could not find any that match my exact (almost default) configuration.
We have 10 users and all 10 are in a group called NOC. Our notification scheme is the default with one change - The NOC group was added to the Issue Created notification. Pretty much everything we have is currently at defaults (we just moved to Jira Service Desk a week ago)
When our monitoring software sends an alert email, it hits a DL that then hits the address that creates a ticket in Jira Service Desk. The Issue gets created and the email to the NOC group flies out to everyone. Except a single person. They DO receive emails when someone manually emails the same DL from above.
I even added her single user to the Issue Created notification to no avail.
We've deleted *all* outlook rules and still nothing.
The Notification Helper thing acts as expected - says she should get the notification because she is in the NOC group.