The Postal Service does not permit pens, pencils, key rings, bottle caps, and other similar odd-shaped items in letter-size or flat-size paper envelopes unless they are wrapped within the other contents of the envelope to streamline the shape of the mailpiece and to prevent damage during postal processing. If an odd-shaped item is not properly wrapped, it could burst through the envelope and cause injury to employees and damage to USPS processing equipment. Odd-shaped items that are properly wrapped within paper envelopes and sent at letter prices may be subject to the nonmachinable surcharge for First-Class Mail letters or the nonmachinable prices for USPS Marketing Mail letters.
