Custom #10 Envelopes Give Your Brand a Professional Finish Full color printed envelopes are the perfect finishing touch to make your company stand out in the mail. Add your logo or design to your company stationery and see the difference it makes. Choose from a standard #10 envelope or our #10 window envelope. Need your envelopes addressed? We can do that, too. #10 Envelopes FAQ What's the best use for envelopes like these?Standard envelopes are for sending letters, invoices, folded brochures and other letter-sized mail. What is the size of #10 envelopes?#10 envelopes are sized at 9 1/2" x 4 1/8". This is the industry standard size. Are these gum-sealed? Yes, our standard #10 envelopes are gum sealed, which means they have a water soluble gum strip that you lick to seal the envelope. Can the return address be printed on the back flap of the envelope?Yes, we can print your return address and/or logo on the back flap of your envelopes. Can I print envelopes with a full bleed on the sides?At this time, we cannot print envelopes that bleed off the edges. We need at least a .125” blank margin around all sides for proper printing.