You are already using Note to Self Mail and want to test new features and check out the latest improvements? The TestFlight service of Apple provides an easy way to do so. You can join TestFlight by opening this link:
Invitation link to join the TestFlight of Note to Self Mail:
What is TestFlight?
TestFlight is a service by Apple that …
Help developers test beta versions of their apps and App Clips using the TestFlight app. Download TestFlight on the App Store for iPhone, iPad, and Apple TV. […] To test beta versions of apps and App Clips using TestFlight, you’ll need to accept an email or public link invitation from the developer and have a device that you can use to test.https://testflight.apple.com/
To learn more about TestFlight, how to get started an dhow to install and test beta apps, just open https://testflight.apple.com/.