What is the envelope in the upper right corner?

This is the site Private Messaging System (PM).  To access your site PM’s please click on the envelope.  That will show you the active messages you have received. Clicking the "compose new" button in the top right corner of the drop down box will open a pop up box to send a new message. Through that area you can send a PM to any member, as long as you know their username.Go to inbox takes you to the PM system to view your messages.  The system has a predictive field, once you type the first three characters of the name, it will give you options to choose from and narrow it down the more you type.