What is an EcoEnvelope?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. Underneath the Open Here tab, there is a note stating, "This is also your return envelope". After the recipient opens the mail piece, he or she will detach the return slip and place it back into the envelope.