Here's a quick tip for those of you with the HTC One M8. If you're missing notifications for email and calendar on your lock screen, there's a good reason for that. They're not turned on by default. Fixing that is just a matter of diving into the settings and checking a couple boxes.
Here's what to do to get email and calendar notifications on your M8 home screen: Go into the main settings menu. Then choose "Security." Next tap "Notification settings." This is where the options live. By default, your phone will show missed phone calls, voicemail and text message notifications. Email and calendar are unchecked.
So, if you want email and calendar on your home screen, just check the boxes.
A reminder, though, that these are HTC's email and calendar apps. So if you're using, say, Gmail and Google's calendar app (remember that you can download it separately now), you'll still not get them on the stock HTC lock screen.