Current State:

Currently, for unverified Atlassian Account , the user will be silently not receive notifications. This is due to we're validating user verification status to prevent spam email send to the users.
However, users are not aware that this is required as there are no reminders or information sent to the user regarding this.
 

Proposed Future State:

Inform users to verify their accounts in order to receive upcoming notifications. This information can be sent during user creation, or a one-time reminder when the first notification send to the user for work item update/creation.