Three things to try:
1. Don't run your email program when watching Netflix
2. See if your email program has the option to turn off notifications. Since you didn't tell what email program you have I can't be specific
3. See if switching on Windows 10 Game mode turns it off.
Hello & Thanks,
I constantly get email notifications from my live.com account.
It is especially annoying when watching Netflix.
How can I shut this off?