Idea of Open Envelope Icon
When you have email messages available to read you will see a envelope with the top flap open and inside a piece of paper. This shows that you have messages available in your email inbox.
This Open Envelope icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,100 icons, all in the same style and quality.