No need to wait for a designer, you can customize this design yourself with our online designer! It’s simple and easy. Just select the options below and click the “next” button to customize the design with your text/photos/logo etc. Our mailing envelopes are standard 9.5″ X 4.125″ #10 envelopes. They can come with or without windows. All envelopes are printed on 70lb premium natural uncoated stock.