Is Your DIY Envelope Mailable? Here are the USPS Guidelines for Handmade Envelopes
My personal rule of thumb these days is that the more I love my letter and want it to reach its destination, the more standard I make the envelope. If you’re just playing around with some fun, low-stakes pieces, feel free to experiment with your most creative choices. If you really want your piece to arrive safely and on time, however, make you DIY envelopes just a *little* bit creative. More