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PO Boxes Explained: What They Are and When to Use One
A PO box is a numbered mailbox at a postal facility. Learn how it works, when it helps and why couriers often cannot deliver to one.
Updated 14 October 2026 · 2 min read
A PO box (post office box) is a locked, numbered mailbox located inside a post office or postal facility. Mail addressed to the box is held there until the holder collects it. It is a mail address, not a physical location where someone lives.
How a PO box works
The holder rents or is assigned a box at a particular postal facility. Mail is addressed to the box number and the facility's town. The holder collects it using a key or code, or sometimes has it forwarded.
Why people use them
- No reliable street delivery: areas without home delivery or formal street addresses.
- Privacy: separating mail from a home address.
- Stability: a box number does not change when the holder moves within the area.
- Business: a fixed point for receiving mail.
Limits
PO boxes cannot receive everything. Many courier companies cannot deliver to a box because they need a street address and often a signature. Some online retailers refuse boxes for the same reason. Items that are large, valuable or time-sensitive may be undeliverable.
Writing a PO box address
Typically the format is:
- Recipient name
- PO Box and number
- Town or city
- Postal code and region, if used
- Country
Do not put a street address on the same line as the box number; the sorting equipment may read the wrong one.
PO box vs related services
A PO box is one of several collection-point services. See private mailbags and poste restante for others. For how addresses work when delivery is to a door, see how postal addresses are structured.
When a box is not enough
If a courier needs to reach your premises, supply a physical address. An exact-location code can help the courier find it. A PO box alone never locates a building.
Summary
A PO box is a dependable place to collect mail but not a delivery location for every carrier. Check what the sender or retailer accepts before using one.
Frequently asked questions
Can I receive courier parcels at a PO box?
Often not. Many couriers need a street address with a person present, so a PO box may only accept items sent through the national postal service.
Is a PO box the same as a street address?
No. A PO box identifies a mailbox at a postal facility, not a physical building where someone lives or works.