what envelopes need extra postage
Postage Information. The United States Postal Service requires extra postage, called a ânon-machinable surcharge,â on First Class mail sent in non-rectangular or overly thick/rigid envelopes. The Postal Service also requires extra postage when the envelope and enclosures weigh more than one ounce. The non-machinable surcharge impacts Up With Paperâs Treasures brand of greeting cards, which are square and sold with a square envelope.