Three Envelope Mockup
The best Envelope Mockup allows you to showcase your front and back envelope designs in a single mockup. Simply use smart object option for the design insertion and use well-named layers for the rest of customizations.
Free

The best Envelope Mockup for greeting cards, postcards, wedding cards, office documents, paychecks, transactional mail, and statements. Place your artwork on smart object and get a realistic outcome. Place your artwork on both sides and change the background color if you like.