What app does this icon belong to?

[comfortablydumb]

At the top on the notification bar it's the one that looks like a mail or envelope icon. What app does that belong to? I have many that look similar but not sure about this one. Thanks

Did my picture upload?

 

[B. Diddy]

Welcome to Android Central! Swipe down the notification panel and see if it's there. If so, long-press it and tap App Info.