@Ammar222: For additional notification options, please head to Settings > Notifications > Select Email from the 'Recently Sent' section (If you can't see it, tap on 'More' to expand the menu) > Select a notification subcategory > Alert (On) > Show as pop-up (On) > Lock Screen (Show Content).
Can you also head to Settings > Lock Screen > Notifications > Hide Content (Off) > Show On Always On Display (On), to ensure that you're notified when the screen is locked, and when Always On Display is activated.
