C600 Standard Mail Summary C600 describes the basic dimension standards and weight limits for Standard Mail. Each piece must weigh less than 16 ounces.
Lower limits apply to mail claimed at automation rates.
Regular and Nonprofit Standard Mail are subject only to the basic mailability standards in C010 . Merchandise samples whose dimensions exceed these maximums may be sent at the Enhanced Carrier Route rates if mailed using DALs, provided that the samples meet all other applicable standards and the DALs meet the standards in A060 . Flat-size pieces may have short covers as provided in C820.6.2 . There is one surcharge for mail entered at Regular and Nonprofit Presorted rates and a different surcharge for mail entered at Enhanced Carrier Route and Nonprofit Enhanced Carrier Route rates. 3.0 Postal Inspection Standard Mail is not sealed against postal inspection.