If I ship USPS with Priority mail small flat rate box, would that be a problem?
Priority mail has basically three package types: flat rate envelopes, flat rate boxes and priority mail boxes. For either of the flat rate services you must use the USPS packages–they supply them for free–and the cost is the same regardless of the weight of the package. For standard Priority Mail, you can use either USPS supplied free boxes (which are different sizes than flat rate boxes and do not have the words “Flat Rate” printed on them), or you can use your own boxes and mark the Priority Mail. In this case, however, the shipping charges are a function of the package weight. You can print the prepaid shipping label for any type of Priority Mail online. You can not print pprepaid Parcel Post labels online at the USPS site.
