Even with Extended Notifications setting turned off and the app locked the subject of the email is still visible, which completely defeats the purpose of the the app lock. Many services include OTPs or other sensitive information in the subject line of the email which is visible in the notification.

While this can be addressed in the system settings, this is not a solution as those can be changed without unlocking the app.

I propose a setting next to extended notifications that will allow to have the notification show "1 new email" without any information.