Ask anyone who has been through boot camp what got them through it, and a surprising number will say mail call. In every branch, letters are the main line between a recruit and home, and the one thing a family can send that always arrives.
The catch is that boot camp mail has rules of its own: an address you do not have yet, a format that has to be exactly right, and delivery that is slower than you would expect. This guide covers each branch's address, how long mail takes, and where Sandboxx fits in.
Where this comes from: each training command's own family pages and FAQs, and Sandboxx's description of its own service. Address formats below are templates. The exact unit numbers come only from your recruit, and the training commands will not give them out.
Getting the Address
You cannot write until you know your recruit's unit, because every branch sorts mail by it. The Marine Corps is blunt about this: mail "will not reach your recruit without the correct company and platoon number." Here is when each branch's recruits pass it on.
- Air Force and Space Force: trainees get their correct address in the first day or two and are allowed to photograph it and send the photo to family. The Air Force says that whatever your trainee sends you that first week is the correct address unless they tell you otherwise.
- Army: trainees call within 48 hours of reception with their unit of assignment, and each training battalion publishes its own address format on its web page.
- Navy: the address uses your recruit's ship and division numbers, which come from your recruit.
- Marine Corps: at San Diego, the company and platoon arrive in a letter your recruit sends home about two to three weeks into training.
- Coast Guard: the address uses your recruit's company and hall, and recruits start receiving mail daily from the Wednesday of week two.
Until then, write the letters but hold them. A letter sent with a guessed unit may never arrive.
Address Formats by Branch
These are the templates each training command publishes. Fill in the parts in brackets from what your recruit sends you, and copy the rest exactly.
Army (example: a Fort Jackson battalion)
Army addresses differ by training post and by battalion, so use the format on your recruit's own battalion page. This is the published format for 1st Battalion, 13th Infantry Regiment at Fort Jackson, South Carolina:
Navy (Recruit Training Command, Great Lakes)
The street address and ZIP extension depend on which "ship," or barracks, your recruit is in, so use the full address your recruit sends.
Marine Corps (Parris Island example)
Each Parris Island company has its own box number, listed on the depot's Contacting a Recruit page. San Diego publishes its own company addresses, and on either coast the platoon number is the part that matters most.
Air Force (Joint Base San Antonio-Lackland)
The Air Force says older addresses you may find online, with dormitory numbers, are no longer used.
Space Force (trains at Lackland)
Coast Guard (Training Center Cape May)
How Long Mail Takes
Slower than you think. The Navy's boot camp says a standard USPS letter takes anywhere from 5 to 10 business days depending on where it was sent from, and recommends adding another day for the letter to be distributed to your recruit inside the base.
That delay explains the most worrying letter a parent can receive: the one saying nothing has arrived. The Navy says that is usually just letters crossing in the mail, and that by the time you read it, your recruit has your letter.
Two more things worth knowing from the Air Force:
- Mail is never withheld. "Mail is a right, not a privilege." Instructors pick it up Monday to Friday and are never permitted to hold, delay or withhold it. A letter that cannot be handed over that day goes back to the postal center and comes out again on the next delivery day.
- Unit changes reroute mail. If a trainee moves to another flight, they are given the chance to send family the new address, and the Navy notes that mail for a recruit set back in training gets readdressed, which adds delay.
Sandboxx: What It Does and Does Not Change
Sandboxx is a private company, not part of any branch, that many families use for boot camp letters. You write in an app, and Sandboxx prints the letter and ships it. The Air Force mentions it on its arrival page, where trainees can sign up so their unit details reach family through the app.
By Sandboxx's own description:
- Letters submitted by 4:30 p.m. Eastern, Monday through Thursday, are delivered the next day to the base mailroom, shipped by FedEx.
- Each letter includes one photo, and its paid upgrade allows up to four, plus stationery for your recruit to write back.
- It offers optional add-ons such as printed reply prompts to make writing back easier.
What it cannot change is what happens after the mailroom. The Air Force points out that delivery notifications from commercial services show when a letter reached the base postal center, not when your trainee received it, and with up to 7,000 trainees on base at once, sorting and distribution can take days. The Navy says it does not endorse or recommend any particular delivery service, and that a standard USPS letter is the traditional method. Sandboxx is a paid service, so check its current prices before you commit.
Our honest view: if you want speed and an easy way for your recruit to reply, Sandboxx is worth considering. If you prefer paper you can hold, a stamped envelope works in every branch and always has.
What to Write About
- Ordinary news from home. The dog, the weather, who won the game. Normal life is exactly what a recruit misses.
- Encouragement, not worry. Your recruit cannot fix anything at home from boot camp. Save hard news unless they truly need to know it.
- Number your letters. Mail often arrives out of order, and numbers let your recruit read them in sequence.
- Make replying easy. Ask one or two simple questions they can answer in a line. Navy recruits, for example, can only write back during Sunday morning and holiday free time.
Before you add anything to the envelope, read what you can and can't send to boot camp. Some of the most loving things parents mail, like candy, get recruits in trouble.
Frequently Asked Questions
The Bottom Line
Wait for the address, copy the format exactly, and then write often. Mail is slow and arrives out of order, but it is the one channel every branch protects, and the one your recruit will remember.
If you have not heard from your recruit yet, our guide to the first phone call from boot camp explains what to expect and when.