To stop receiving Twitter notification emails:
1. Log in to your Twitter using browser on your desktop computer.
2. Click on your profile icon at the top right of page. Then choose Settings and privacy.
3. On Setting and privacy page, choose Email notification.
You will see the status Email is enable (default). To make disable click Turn off button.
Now you will not receive Twitter notification email.
To set it back receiving the notifications, just Turn on it back.