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Yes, USPS delivers packages to US PO boxes, as long as the parcel fits the box or the post office can hold it for pickup. Private couriers generally do not deliver to PO boxes, so the carrier choice matters more than the address itself. LetterAgent labels are Canada-only and do not cover a US PO box shipment.
A PO box is a locked box inside a post office, rented by the recipient, and only USPS staff can open it. When your parcel arrives, staff place it in the box if it fits, or in a larger parcel locker in the lobby with a key left in the box, or they hold it at the counter with a pickup slip in the box. The recipient then collects it with a key or ID. That system is why USPS can deliver to a PO box and a courier cannot: the courier has no access to the box, the locker, or the counter.
Size is the main limit. PO boxes come in several sizes, and a small box will not hold much more than letters and small parcels. A parcel that is too large for the box is not returned on the spot; the post office holds it and leaves notice, but the hold lasts only a limited time before the parcel goes back to you. If you know the recipient has a small box, ask them before shipping a bulky item, or check whether their post office offers a street address version of their box, which some locations provide for parcel deliveries.
| Carrier | Delivers to a US PO box? | What happens instead |
|---|---|---|
| USPS | Yes, for parcels that fit or can be held | Box, parcel locker, or counter pickup with notice |
| UPS | Generally no | Shipment may be handed to USPS for final delivery, or refused |
| FedEx | Generally no | Shipment may be held, rerouted, or returned |
| Amazon delivery | Usually no for its own drivers | May go through USPS, or ask for a street address |
Write the recipient's name, then "PO Box" followed by the number, then the city, state, and ZIP code, each on its own line. Do not add a street address on the same label unless the recipient has told you their post office accepts a street-address format for their box; mixing the two can confuse sorting and delay the parcel. Double-check the box number digit by digit, since a single wrong digit sends the parcel to a stranger's box, and the post office will not open boxes to hunt for it.
Include your return address on the label, and keep it legible. If the parcel cannot be delivered, for example because the box rental lapsed or the hold expired, a clear return address is what gets it back to you instead of into an unclaimed-parcel process. For a valuable parcel, add tracking and, where the service offers it, signature or delivery confirmation, so you can see when it reached the post office and when it was collected.
Signature services work differently at a PO box, since there is no doorstep handoff. A signature parcel is usually held at the counter, and the recipient signs when they collect it, which can delay delivery by a day or more if they do not visit the post office promptly. Tell the recipient a signature parcel is coming, so they check their box and collect it before the hold expires.
Insurance and tracking follow the parcel, not the box, so they work as normal. Restricted items follow the same rules as any USPS parcel: hazardous goods, perishables, and oversized items each have their own limits, and a PO box does not change them. One practical limit is weight and bulk for rural post offices, where counter space is small and a very large parcel may be held only briefly. When in doubt, ask the recipient which size their box is and whether they can collect a held parcel quickly.
No. LetterAgent shipping labels are Canada-only, flat-rate Canada Post Xpresspost, with a 5 kg maximum, and they do not cover shipments to the United States at all, PO box or street address. For a Canadian shipment, the flow is a per-label quote, your approval of the exact price, a one-time Stripe payment, and a label PDF you print and drop off. For a US PO box parcel, buy USPS postage through a USPS channel instead, and choose a USPS service, since that is the carrier that can actually reach the box.
Ready to ship it? Get a shipping label with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and get your label.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
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