The address block, exactly
Publication 28 section 261 is unambiguous: "Use the words GENERAL DELIVERY, uppercase preferred, spelled out (no abbreviation), as the Delivery Address Line on the mailpiece." Each general delivery record carries the 9999 add-on code. Section 262 requires that the code applied be the correct one for the general delivery record in the ZIP+4 file, which is the polite way of saying that a town with several offices has a specific one that holds this mail, per pe.usps.com, checked 2026-07-28.
Who it is for, and for how long
The recipient services rules call general delivery "intended primarily as a temporary means of delivery", for transients and customers not permanently located, and for customers who want Post Office box service when boxes are unavailable. It is normally offered at one facility per Post Office and a customer may use only one such location. A postmaster may refuse or restrict it where someone cannot present suitable identification, or where the volume cannot reasonably be accommodated. Holding is capped: "Each general delivery mailpiece is held for no more than 30 days, although a shorter time period may be requested by the sender." All from DMM 508.6 at pe.usps.com, checked 2026-07-28.
What the sender should do first
The rules put one job on the sender before anything ships, stating that "Prior to mailing, customers should contact the destination Post Office to determine the authorized facility or facilities and their applicable ZIP Code(s)." Do that, then buy the postal row on the quote. Our checkout will run the destination through carrier address records before taking payment, so a wrong office ZIP surfaces there rather than three states later.
