What are the postal requirements for my envelopes ?
It is important to keep in mind U.S. Postal Service requirements when designing your envelopes. All mail .25 inches thick or less must be: 1. Rectangular in shape, 2. At least 3.25 inches high, and 3. At least 5 inches long. A mail piece must be at least .007 (7 pt.) inches thick when it does not exceed 4.25 inches in height and 6 inches in length. A mail piece must be at least .009 (9 pt.) inches thick if it is either greater than 4.25 inches in height or greater than 6 inches in length or both.