The EcoEnvelope is one of the most exciting and newest innovations in the Direct Mail industry, and Click2Mail is proud to offer it to you when you send Courtesy Reply letters. The EcoEnvelope is a #10 envelope made of 100% post-consumer recycled materials. There is a single, clear plastic pane through which the recipient address shows. When a mail recipient receives the direct mail piece, they open it by pulling a tab that says Open Here.