An FPO address looks like a US postal address, and for postage purposes it is one. The mail rides USPS to Naval or Marine Corps sorting points and travels the rest of the way through the military postal system. UPS and FedEx cannot deliver to it. What the sender has to get right is the address block and, on any package, the customs form. USPS Military and Diplomatic Mail guidance, read 2026-08-11.
The Navy takes the box from the postal system, not from a carrier truck.
Fleet Post Office addresses do not use a street or a city. The sailor's unit or ship handles that at the far end. The lines the sender writes are the ones the postal system uses to identify which regional pipeline the mail belongs in.
SEAMAN JOSEPH SMITH UNIT 100100 BOX 4120 FPO AP 96691-0001
Three letters, three pipelines. FPO AE covers Europe, the Middle East, Africa and Canada. FPO AP covers the Pacific. FPO AA covers the Americas outside the continental United States. The nine-digit ZIP identifies the specific unit or ship inside that pipeline; the sailor gives it to the sender, and getting one digit wrong misroutes the box by an ocean.
| Class | Reaches FPO? | Notes |
|---|---|---|
| First-Class Mail letters and postcards | Yes | Same postage as domestic; forms 3800 and 3806 available |
| USPS Ground Advantage | Yes | Domestic postage; surface transportation applies for prohibited-air items |
| Priority Mail and Priority Mail Flat Rate | Yes | Free APO/FPO flat rate boxes carry a per-box military-address discount at the counter |
| Priority Mail Express | Yes, to most FPO ZIPs | Delivery-time commitments are ashore; onward time to the ship or unit is not part of the commitment |
| Media Mail | Yes for eligible content | Books, records, sound recordings; the eligibility rules are the same as domestic Media Mail |
The one class that does not fit is anything sold by UPS or FedEx. Neither reaches an FPO destination. A shopper who cannot pick USPS at checkout has to arrange delivery to a stateside address and reship into the military postal system.
A package to an overseas FPO ZIP is treated as international for customs purposes even though the postage is domestic. USPS generates PS Form 2976-R when the label is printed online, and that is the form most senders will use for a care package under 16 ounces of contents value. Heavier or higher-value parcels use PS Form 2976-A, the multi-copy form. Printing the label at usps.com bakes the customs form into the flow; buying postage at the counter without one is what leaves boxes stuck at the origin.
Restricted items on the FPO list are the ones a sailor cannot legally receive at the destination: alcohol at any strength, hazardous materials of any kind, most obscene material, and any drug not held under a valid prescription for the addressee. Overseas destinations layer their own bans on top (pork products into some Muslim-country ports, for example). USPS refuses these at induction; the military postal service refuses them at the pier.
USPS offers Priority Mail APO/FPO Large Flat Rate Boxes free through the Postal Store, delivered to the sender's home. Any civilian can order them and can use them for military-address shipments; the same box sent to a civilian address is not free.
Twelve inches on a side and about six inches tall, the APO/FPO Large Flat Rate Box holds a couple of paperbacks, a pair of shoes, and enough small treats to feel like home. The empty box weighs almost nothing; the fill decides the shipping charge.
The price at checkout is lower than the same box sent domestically, because USPS applies a per-box discount off the retail Priority Mail flat rate when the destination is a military ZIP. The exact figure is on the current USPS price list; the discount principle has been steady across recent revisions.
Order the boxes at store.usps.com, keep them at home, and print a label whenever the next care package is ready. Neither the box nor the shipping is time-boxed to a holiday window.
The other Priority Mail flat rate boxes and envelopes ship to FPO destinations too, at their standard flat rate. The military-address discount belongs to the APO/FPO large box only.
USPS updates the APO/FPO service list and price schedule from time to time. The rules above are what USPS published on the date shown; a program running regular care packages should check the current text before printing labels.
No. UPS and FedEx do not deliver to APO, FPO or DPO addresses. Only USPS carries the mail into the military postal system, where the Navy takes it the rest of the way to a ship or overseas installation.
Recipient name (rank if known), Unit or PSC number and box, then FPO AA / AE / AP with the nine-digit ZIP. No street, no city, no country. The three-letter state code tells the sorting machine which regional pipeline the mail belongs in.
Priority Mail, Priority Mail Express, USPS Ground Advantage and First-Class Mail (for letters and small packages) all reach FPO addresses, with the same size and weight limits as their civilian equivalents.
Yes for any package to an overseas FPO ZIP. PS Form 2976-R is generated online for most shipments; heavier or higher-value parcels use PS Form 2976-A. USPS treats FPO parcels as international for customs purposes even though the postage is domestic.
A free Priority Mail flat rate box available to any sender through the Postal Store, sized to fit standard care-package contents. USPS applies a per-box discount off the retail Priority Mail flat rate when the destination is a military address, which is why the sender sees a lower total at checkout.