An APO, FPO, or DPO address uses three lines: the recipient’s name, a unit or PSC number with a box number, and a final line combining the post office type (APO, FPO, or DPO), a two-letter military state code (AA, AE, or AP), and the ZIP. To fill out an APO address correctly, write those three lines in block capitals, leave off any city or country name, and skip punctuation on the last line. Get any of that wrong and USPS may divert your package into international mail, where it stalls or comes back.
The Three-Line Format
Every APO, FPO, and DPO address is exactly three lines. Here is a standard Army or Air Force example from USPS:1USPS. Military and Diplomatic Mail
PFC JOHN DOE
PSC 3 BOX 4120
APO AE 09021
A Navy or Marine Corps address follows the same shape but uses “FPO” and typically “UNIT” instead of “PSC”:
SEAMAN JOSEPH SMITH
UNIT 100100 BOX 4120
FPO AP 96691
A Diplomatic Post Office address for a civilian at a State Department post looks like this:
JOHN ADAMS
UNIT 8400 BOX 0000
DPO AE 09498-0048
Write everything in clear block capitals. If you are printing the label at home, use a plain sans-serif font at 10-point or larger, and always put your full domestic return address in the upper left corner. Mail sent without a usable return address that cannot be delivered will be opened at a USPS Mail Recovery Center; if nothing inside identifies the sender, the package is disposed of.2USPS. Military Mail: FAQ
What Goes on Each Line
Line 1: The Recipient’s Name
Write the recipient’s full name. Rank before the name is optional but common, and it can help clerks route mail inside a large installation. Standard abbreviations work: PFC, SGT, CAPT, and so on. For a civilian at a diplomatic post, use the full name with no title.
Line 2: Unit or Box Number
This line tells the destination post office which mailbox belongs to the recipient.3USPS. How is Military Mail Processed? The format depends on the branch:
- Army and Air Force personnel usually get a Postal Service Center number followed by a box, written as “PSC 3 BOX 4120.”
- Navy and Marine Corps members generally get “UNIT” plus a unit number and box, such as “UNIT 100100 BOX 4120.”
- Sailors assigned to a ship use the ship’s name and hull number in place of the unit number.
- DPO recipients use “UNIT” and a box number assigned by the State Department.
Never write just “PSC 3” or “UNIT 100100” without the box number. The clerk at the receiving end has no way to identify the specific mailbox and the package will sit.
Line 3: Post Office Code, State Code, and ZIP
The third line is where most mistakes happen. It combines three pieces of information, separated only by single spaces, with no commas or periods:
- The post office type: APO for Army or Air Force, FPO for Fleet or Navy, or DPO for Diplomatic.
- The military “state” code: AA for Armed Forces Americas, AE for Armed Forces Europe, the Middle East, Africa, and Canada, or AP for Armed Forces Pacific.
- The five-digit ZIP, or ideally the full ZIP+4 for faster sorting.
So the line reads “APO AE 09021” or “FPO AP 96691” or “DPO AE 09498-0048.” The recipient or their command will supply the correct state code and ZIP. If you do not have both, ask before guessing.3USPS. How is Military Mail Processed?
Mistakes That Cause Delays
The single most common error is writing a city or country anywhere on the label. If your service member is stationed in Germany, do not put “Germany” or “Stuttgart” on the envelope. USPS routes APO, FPO, and DPO mail through domestic sorting facilities, and any foreign geography on the label can push the package into the international mail stream, where it gets stuck or returned.3USPS. How is Military Mail Processed?
Other mistakes that slow delivery:
- Adding punctuation to the last line. Write “APO AE 09021” with no commas, periods, or slashes. USPS sorting equipment reads these lines optically and stray marks confuse the scanners.
- Using the wrong post office code. An Army member’s address uses APO, not FPO. Swapping them routes the mail to the wrong processing facility.
- Using the wrong state code. AA, AE, and AP cover different parts of the world, and each ZIP block is tied to one of them. AE with a Pacific ZIP will not work.
- Omitting the box number, as noted above.
- Handwritten labels that are hard to read. Block capitals, printed cleanly, are what the scanners expect.
Customs Forms Are Required for Packages
The address is only half the job. Anything beyond a plain letter needs a customs declaration, and the old paper green-and-white slips are no longer accepted. Since 2020, USPS has required customs data for military and diplomatic mail to be submitted electronically; packages presented with handwritten customs forms will not be accepted at the counter.4USPS. PS Form 2976-R Acceptance Policies Including Military Mail
You have two ways to comply. You can create the customs label online through USPS Click-N-Ship or a comparable shipping platform, which transmits the data automatically and prints a label you attach at home.1USPS. Military and Diplomatic Mail Or you can fill out PS Form 2976-R by hand as a worksheet and bring it to a Post Office, where a clerk keys the data in and prints the compliant label for you.5USPS. Customs Forms
List every item with a specific description, its material, its purpose, and a dollar value. “Gift” or “stuff” is not enough and can cause a hold or return. “Cotton t-shirt, personal use, $15” is the level of detail customs officers expect.5USPS. Customs Forms
Contents That Can Get a Correctly Addressed Package Rejected
Even a perfectly addressed package will be refused, held, or returned if it contains something restricted. APO, FPO, and DPO mail ships at domestic postage rates but remains subject to international mailing rules, host-country law, and Department of Defense restrictions.6USPS. Shipping Restrictions and HAZMAT – What Can You Send in the Mail? Commonly restricted or prohibited items include alcohol, firearms and ammunition (ammunition is prohibited entirely), explosives, gasoline and liquid mercury, perishable food without special packaging, and tobacco to certain ZIP codes. Restrictions vary by destination ZIP, so check the USPS International Country Listings before you pack.
Lithium batteries deserve their own note because care packages so often include electronics. Lithium batteries, rechargeable or not, may only be sent to an APO, FPO, or DPO address when installed inside the device they power. Loose batteries and spares packed alongside a device are prohibited. Even installed, quantities are capped at four cells or two batteries per shipment, with no more than two such mailpieces per mailing. Cushion the device so it cannot shift, use rigid outer packaging, and do not place any lithium battery markings on the outside of the box.7Postal Explorer. USPS Packaging Instruction 9E
Address the three lines the way USPS shows them, keep any foreign geography off the label, submit customs data electronically for anything larger than a letter, and confirm what is inside the box is allowed. Do those four things and your mail will move through the military postal system the same way any domestic package does.