#9 Envelopes are commonly used for sending donations, payment vouchers, and invoices. The size of standard #9 envelopes is 3 7/8 x 8 7/8 inches, making them perfect to fit into #10 envelopes, for return mailings.  These envelopes are suitable for home or office mailing projects, and are available in a variety of colors, ranging … [Read more…]