A Certificate of Mailing is a USPS extra service that proves you mailed an item on a specific date. It creates an official record of the mailing date only. It does not record delivery, it does not obtain a signature, and it does not insure the contents. USPS sells it with the mailing and notes that the Postal Service does not keep copies of the receipts, so the receipt you receive is the record you must keep.
This page covers the definition, the forms, who it suits, and where it stops being enough. If you are weighing it against a tracked service, read our side-by-side on Certificate of Mailing vs. Certified Mail instead.
What a Certificate of Mailing Proves and What It Does Not
| Question | Certificate of Mailing |
|---|---|
| Does it prove the date the item was mailed? | Yes. That is its entire function. |
| Does it show delivery? | No. USPS states it does not provide a record of delivery. |
| Does the recipient sign for it? | No. No signature or receipt is obtained at delivery. |
| Is the item insured against loss or damage? | No. USPS states no insurance is provided. |
| Can it be used for international mail? | Yes, in addition to domestic mail. |
| Does USPS keep a copy of the receipt? | No. USPS states the Postal Service does not keep copies of Certificate of Mailing receipts. |
Everything on that table is drawn from the USPS service description. Source verified on USPS: https://faq.usps.com/s/article/Certificate-of-Mailing-The-Basics.
The Forms: PS Form 3817, PS Form 3665, and the Firm Mailing Book
The form depends on how many pieces you are mailing at one time.
- PS Form 3817, Certificate of Mailing is used for a shipment containing one or two items, domestic or international.
- PS Form 3665, Certificate of Mailing - Firm is used when a shipment contains three or more items. USPS also lists it for unregistered First-Class Mail International, First-Class Package International Service, Free Matter for the Blind, and Airmail M-Bags.
- PS Form 3877, Firm Mailing Book for Accountable Mail is the multipage bound book used for multiple accountable pieces presented at once. It removes the need to produce an individual receipt for each article.
USPS also publishes submission thresholds that matter to volume senders. Mailings of fewer than 50 pieces and less than 50 pounds presented at one time go to a retail Post Office. Mailings of 50 pieces or 50 pounds and more present hardcopy PS Form 3665 to a Business Mail Entry Unit or authorized Detached Mail Unit. All of this is in the USPS service description cited above, and privately printed or computer-generated versions of these forms require USPS approval under DMM 503.
What Mail Classes Can Carry a Certificate of Mailing?
USPS lists Certificate of Mailing as available with First-Class Mail, Priority Mail, Bound Printed Matter, Library Mail, and Media Mail. Fees are charged in addition to regular postage, and USPS says the fee depends on whether the certificate is purchased for an individual article or for an individual article with a Firm Mailing Book. Check the current fees on the USPS postal rates page before you budget a large run.
How You Get One
- Prepare the mailpiece with its normal postage for the class you are using.
- Complete the applicable form (PS Form 3817 for one or two items, PS Form 3665 for three or more).
- Present the mail and the form to USPS. Retail handles small volumes; larger volumes go to a Business Mail Entry Unit.
- USPS dates and validates the certificate at acceptance.
- Keep the validated certificate. There is no backup copy held by USPS.
When a Certificate of Mailing Is the Right Choice
It fits when the only fact you need to establish is that something was mailed on a certain date, at a modest cost, and when you do not need to prove that it arrived.
- You are mailing a routine filing and want a dated record without paying for tracking or signature services.
- You mail at volume and need a low-cost per-piece mailing record for internal reconciliation.
- You are sending to a destination where a signature service is impractical, but you still want a dated mailing record.
- Your own policy requires evidence of mailing, and nothing more.
It does not fit when anyone will later ask whether the item arrived, who signed for it, or what happened between mailing and delivery. For that you need a tracked service, and usually a signature record.
Where People Get a Certificate of Mailing Wrong
- Assuming USPS can produce a copy later. It cannot. Photograph or scan your validated receipt the day you mail it, and store it somewhere searchable.
- Treating it as delivery proof. A dated mailing record answers a mailing-date question. It does not answer a receipt question.
- Assuming it insures the contents. It does not. Choose a mail class or service that provides the coverage you need.
- Buying the wrong form for the volume. One or two items is PS Form 3817. Three or more is PS Form 3665. Large presentations go to a Business Mail Entry Unit.
- Confusing it with a mailing receipt for a tracked service. They are separate services with separate fees and different proof.
When You Need Proof of Delivery Instead
If the question you are trying to answer is "did it arrive, and who signed," a Certificate of Mailing cannot answer it. Certified Mail can. Certified Mail provides a mailing receipt, a USPS tracking number, and a signature requirement at delivery, and it can be combined with Return Receipt for a signature record. Electronic Return Receipt delivers that signature record digitally rather than on a paper card.
That is the trade you are making — the certificate is cheap and proves the date, while Certified Mail costs more and proves the journey. Choose by what your file has to contain, not by which is cheaper.
If a statute, court rule, or contract specifies a mailing method, confirm the requirement with counsel before you mail. A mailing provider can document what happened; it cannot decide whether your chosen method satisfies a legal requirement.
Keep the Mailing Record Where You Can Find It
Whether you use a Certificate of Mailing, Certified Mail, or both, the record is only as good as your ability to retrieve it. Mailings created through Certified Mail Labels keep proof of mailing, USPS acceptance scans, tracking events, delivery confirmations, and signature records in the free 10-Year Compliance Archive, searchable for ten years at no extra charge.
Get Delivery Proof, Not Just a Mailing Date
Start with create and print live-postage Certified Mail labels online: no monthly fees, no contracts, no equipment lease, and no postage meter, and you pay less than Post Office counter rates. Prefer to stay hands-off? Our Print & Mail service prints your uploaded PDF, inserts it, applies postage, and hands the mail to USPS the same business day for orders received by 5:00 PM Eastern, and every full-service mailing includes a notarized affidavit of mailing. High-volume teams can run Excel/CSV batch label tool or API and SFTP automation with USPS SCAN Forms. Add Electronic Return Receipt for an electronic signature record, follow every piece with Certified Mail tracking, and keep the proof in your free 10-Year Compliance Archive. Current postage and service fees are always on the USPS postal rates page.
Certified Mail Labels is a mailing service, not a law firm. We do not provide legal advice. Confirm which mailing method your obligation requires with counsel or the issuing agency.
Frequently Asked Questions
What is a Certificate of Mailing?
A Certificate of Mailing is a USPS extra service that provides evidence you mailed an item on the date you say you did. USPS dates and validates the certificate at acceptance, and it serves as a record of the mailing date only.
Does a Certificate of Mailing prove delivery?
No. USPS states that a Certificate of Mailing does not provide a record of delivery, and no signature or receipt is obtained when the item is delivered to the recipient.
Does the Post Office keep a copy of my Certificate of Mailing?
No. USPS states the Postal Service does not keep copies of Certificate of Mailing receipts, which is why you must keep your validated receipt and store a scan or photo of it.
Which form do I use for a Certificate of Mailing?
PS Form 3817 is used for shipments containing one or two items. PS Form 3665, the Certificate of Mailing - Firm, is used when a shipment contains three or more items. PS Form 3877, the Firm Mailing Book for Accountable Mail, is used for multiple accountable pieces presented at one time.
Which mail classes can be sent with a Certificate of Mailing?
USPS lists Certificate of Mailing as available with First-Class Mail, Priority Mail, Bound Printed Matter, Library Mail, and Media Mail, and it can be used for domestic or international mail. Fees are charged in addition to regular postage.
Should I use a Certificate of Mailing or Certified Mail?
Use a Certificate of Mailing when you only need to prove the mailing date at the lowest cost. Use Certified Mail when you also need a tracking number, delivery status, and a signature at delivery, and add Return Receipt when you need the signature record itself.