Ancillary Service
(1) Formally, an optional Special Service purchased for a fee in addition to the postage applicable to the mail class or product. These optional services vary in nature, and most may be purchased only for specific mail products or mailpiece shapes. Ancillary Services include Address Correction Service; Applications and Mailing Permits; Business Reply Mail service, Merchandise Return Service, and Bulk Parcel Return Service; Certified Mail; Certificate of Mailing; Collect on Delivery; USPS Tracking; Insurance; Parcel Airlift Service; Registered Mail; Return Receipt; Restricted Delivery; Shipper- Paid Forwarding; Signature Confirmation; Special Handling; and Stamped Envelopes, Stamped Stationery, and Stamped Cards. (2) Informally, forwarding, return, disposal, or address correction service provided by USPS for undeliverable-as-addressed (UAA) mail. The mail class or product determines the availability of a service and any charge if and when the service is rendered.