Can You Send Certified Mail to a PO Box?

Short answer: yes. You can send certified mail to a PO box, and you don't even need the recipient's street address to do it. The only twist is what happens on the delivery end: because certified mail requires a signature record, the recipient may need to claim it at the counter unless they have Signature on File. Here's exactly how it works, what it costs, and what happens if no one collects it.

Can you send certified mail to a PO box?#

Yes. USPS is explicit that all mail classes and services may be sent to a PO box, and certified mail is one of them. Address the letter to the PO box the way the recipient uses it—"PO Box 123"—and you're set. The box address is a valid delivery address on its own, so there's no need to track down a physical street address.

One thing to get right before you mail: certified mail requires a signature from the addressee, and you enter the recipient's complete name and address on PS Form 3800, the certified mail receipt. That's the same form and process whether the destination is a house, an office, or a PO box.

How does certified mail get delivered to a PO box?#

This is where a PO box behaves differently from a street address. A carrier can drop ordinary letters straight into the box—but certified mail needs a signature record, and USPS keeps a delivery record that includes the recipient's signature.

Most PO-box certified-mail deliveries follow this sequence:

1. A pickup notice goes in the box. When certified mail arrives for a PO box, USPS leaves a notice—PS Form 3849, "We ReDeliver for You!"—in the box instead of the letter.
2. The box holder takes the notice to the counter. In USPS's own words, it's a "notice that you can take to a window clerk to collect your item(s)." For a PO box, redelivery isn't offered—you collect from the window clerk.
3. They show ID and sign. The box holder, or an authorized agent with acceptable identification, signs for the item at the retail counter and walks away with the letter.

There is one important exception: USPS says PO Box customers can keep a Signature on File. When that is active, USPS can place signature-required mail in the PO box or a secure parcel locker instead of making the recipient wait in line to sign. So the practical rule is: no Signature on File usually means a pickup notice and counter signature; Signature on File can mean box or locker pickup.

What does it cost to send certified mail to a PO box?#

Nothing extra. Sending certified mail to a PO box costs exactly the same as sending it anywhere else—there's no PO box surcharge. You pay the certified fee plus regular First-Class postage:

For a 1 oz stamped First-Class letter, the January 2026 base cost is:

• Certified Mail fee: $5.30
• First-Class postage: $0.78
• Total without return receipt: $6.08
• Electronic return receipt: add $2.82
• Mailed return receipt (green card, PS Form 3811): add $4.40

Those rates are current until the scheduled USPS July 12, 2026 price change, when the Certified Mail fee rises to $5.55 and a 1 oz stamped First-Class letter rises to $0.82. Re-verify rates before publishing. For the full breakdown by weight and add-on, see our certified mail cost guide.

How do you get proof of delivery?#

Proof is the whole reason people use certified mail, and it works the same to a PO box as anywhere else:

• Tracking. Every certified letter gets a tracking number so you can follow it from mailing to pickup. You'll see when it's available at the counter and when it's collected.
• Return receipt. Add a return receipt and you get proof of who signed—electronically ($2.82) or as the classic mailed green card ($4.40). USPS keeps the delivery record, signature included.

Certified mail doesn't move any faster than regular mail—it travels at First-Class speed, so plan for the usual 1–5 days in transit. What you're buying is proof, not speed.

What happens if it isn't picked up?#

A PO box holder has to physically go to the counter to claim certified mail, so unclaimed letters are more common than you'd expect. When that happens, USPS holds the item and then sends it back:

• It's held at the Post Office for 15 days and returned to sender on the 16th day.
• Even if it comes back, your mailing receipt still proves you sent it on the date stamped—often the thing that actually matters for a deadline or a legal notice.

If your letter returns, read what an unclaimed certified letter means before you resend—for many legal purposes, a documented attempt still counts.

Sending regular mail without a trip to the post office#

Certified mail means a Post Office trip on the receiving end—and, unless you use an online service, on the sending end too. For everyday letters that don't need a signature, you can skip that entirely.

Postmarkr sends tracked First-Class letters online today—upload a PDF, we print and mail it, starting at $1.50 for the first page. Certified mail is coming soon. So if you just need a letter delivered with tracking, you can send your first letter from your laptop; if you specifically need certified mail today, USPS or an online certified-mail service is the way to go.

[Send Your First Letter](/how-it-works)

• ✓ No subscription required
• ✓ No minimums
• ✓ Create account free
• ✓ Pay per piece — send 1 or 1,000
• ✓ Delivery guarantee — lost in the mail? We resend for free