5x7 envelopes - Please note this envelope size is not mailable via USPS. Small in size but big in style, our #3 mini envelope (2-1/8 x 3-5/8) is another multifunctional envelope from our extensive assortment of fine stationery. Designed like a standard-sized envelope with a pointed flap, this miniature version is ideal for a variety of usages, such as coordinating with your favorite seating or place cards, as well as housing gift-cards on packages or flower arrangements; it may also be used for standard-sized business cards (2 x 3 dimension).