Hi bbains,
As Outlook is a third-party app, it would be best to contact Microsoft for the details regarding their app.
That said, if you're able to confirm in the Settings for Outlook on your iPhone if there is an option to toggle notifications to your liking, that should mirror over to the Apple Watch.
See more info about mirroring notifications on Apple Watch here:
"Customize your Apple Watch notification settings
- Open the Apple Watch app on your iPhone, then tap the My Watch tab.
- Tap Notifications.
- Tap an app to see its options. To use the same notification settings on apps that appear on both your Apple Watch and iPhone, tap Mirror my iPhone. Some apps allow you to customize your notifications. Tap Custom, then choose an option:
- Allow Notifications: Notifications appear in Notification Center and your Apple Watch alerts you.
- Send to Notification Center: Notifications are sent directly to Notification Center without your Apple Watch alerting you.
- Notifications Off: The app sends no notifications.
- If you customize an app's notifications, you can also group notifications from that app. Tap Notification grouping, then choose an option: Off, Automatically, or By App.
Some apps offer further customization, while others only let you turn off Apple Watch notifications completely. Scroll down to the Mirror iPhone Alerts From section and turn off the setting next to the app. "
Cheers!