If you ever needed to stop a user(s) from getting email auto-alerts, don't worry you don't have to weed through a ton of controls. Your preferences can be as simple as just 2 checkboxes.
- Email Notifications based on assignments or updates
- Daily, scheduled email notifications
See the User Preferences page to clarify what type of emails you are getting.
Second, you can also check your System Wide Auto-Alert Notifications to drill into what specific notifications are going out.