Hello Jaychi007,
You can customize notifications on your Apple Watch using the steps below:
1. Open the Apple Watch app on your iPhone.
2. Tap My Watch, then tap Notifications.
3. Tap the app (for example, Messages), tap Custom, then choose an option. Options may include:
• Allow Notifications: The app displays notifications in Notification Center.
• Send to Notification Center: Notifications are sent directly to Notification Center without your Apple Watch making a sound or displaying the notification.
• Notifications Off: The app sends no notifications.
You can also find those steps in this resource: Change notification settings on Apple Watch - Apple Support
Should you still continue to get those notifications, are they coming from the built-in Mail app or the Outlook app?
Let us know, and we'll keep moving forward from there.