Coverage for a shipper (owner/sender) for property damage or loss of goods in transit through the post office. A trip transit insurance policy specifically excludes coverages on property sent through the post office since that agency is not a common carrier and does not incur the liability of a common carrier. This is why additional coverage must be purchased in the form of parcel post insurance, even if a business has a trip transit insurance policy. Parcel post insurance is sold by the post office in the form of a certificate, which covers property in its custody. It is issued on an all risks basis, subject to exclusions of spoilage, and financial instruments such as bills, currency, deeds, notes, and securities.