Format Requirements:

CMRAs inform their customers, during the application process, of all the customers' responsibilities to continue or to start receiving mail services offered by the CMRA. The CMRA also provides its customers with the format to be used for the delivery of mail to the CMRA. If the CMRA's customers refuse or fail to comply with Postal Service regulations governing the operations of a CMRA, the CMRA must terminate the relationship with the customers or deny the application of customers that refuse or fail to comply with regulations.

Source USPS