Full page pop ups on Galaxy s4 since updating to Lollipop

[NYER566]

This one full page pop up is driving me crazy. I can't find out what is causing it. It pops up whenever it feels like it. Its a black background with a clock on it and has at the bottom an email type of icon. I have no idea where this is coming from. I have tried everything to get rid of it by deleting apps to see if it may be the app causing this pop up but nothing works. If anyone has this issue please let me know. It pops up so fast then goes away as fast as it pops up. I am dying to get rid of this annoying full page pop up. Any help would be appreciated. I don't want to have to do a full restore.

 

[N4Newbie]

Does it look like any of these images? https://www.google.com/search?q=gal...hUKEwi-ku-izvDKAhVFeT4KHZUrCtAQsAQIRg#imgrc=_

If so, which one?