5-3 Dimensions and Shape Standards for Automation-compatible Enveloped Letters Containing Disc

Each enveloped letter must meet the basic standards for machinable letters and have the following characteristics:

1. Length: Not more than 9.75" or less than 7.25".
2. Height: Not more than 6" or less than 5.5".
3. Thickness: Not more than 0.25" or less than 0.009".
4. Weight: Not more than 3 ounces.
5. Paper basis weight: Based on the length of the piece, as follows:
1. Up to 8" long: A minimum 70-pound book-grade paper or equivalent.
2. Over 8" and up to 9.75" long: A minimum 80-pound book-grade paper or equivalent.

Note: If the mailpiece is made of the minimum basis weight paper, the disc must be contained in a protective sleeve.

6. Window envelope: Not allowed unless the Postal Service has tested and approved it.