Final answer:
An FCM package over 13 ounces must be mailed using Priority Mail through the USPS, offering faster delivery and additional services.
Step-by-step explanation:
When a First-Class Mail (FCM) package weighs over 13 ounces, it typically must be sent as Priority Mail. First-Class Mail is an affordable method for sending standard-sized, single-piece envelopes and small packages weighing up to 13 ounces with delivery in 3 to 5 business days.
However, if the package exceeds that weight, then the United States Postal Service (USPS) requires that it be mailed using Priority Mail service.
Priority Mail service is faster, usually delivering within 1 to 3 business days, and offers additional benefits like tracking and insurance options.
It is essential to follow USPS guidelines to ensure that the package is sent correctly and arrives on time.