Proof of mailing: the USPS options and what each one proves

Proof of mailing is a dated record that the Postal Service accepted your letter. It answers one question: was this sent, and on what day? It does not answer whether it arrived. USPS has no single product by that name. It has four things that do the job, and they differ in price, in what they record and in who keeps the record.

The rules on this page come from USPS: sections 503 and 608.11 of the Domestic Mail Manual, the USPS help article Certificate of Mailing: The Basics, the USPS statement Postmarking Myths and Facts of 2 Jan 2026 and Notice 123 for prices. We read them on 13 Nov 2026. Certisent is not affiliated with USPS.

The short version

USPS itself lists the options. In its January 2026 statement on postmarks it says: "Customers who wish to retain a record or proof of the date on which the Postal Service first accepted possession of their mailpiece(s) may purchase a Certificate of Mailing. Registered Mail and Certified Mail services also provide mailing receipts for individual mailpieces." A fourth route, a postmark applied at the counter, puts the date on the envelope itself.

	What you keep	What it shows	Delivery record	USPS fee, on top of postage
Certificate of Mailing (PS Form 3817)	The certificate, round-dated by the clerk	Sender, addressee and the date the piece was presented	No	$2.45
Certified Mail (PS Form 3800)	A numbered receipt, round-dated if you present it to a clerk	The number, the addressee and the acceptance date	Yes	$5.55
Registered Mail	A registration receipt	The registration and its date	Yes	From $20.90
Manual (local) postmark at the counter	Nothing. The postmark is on the envelope	The retail unit and the date the piece was accepted	No	No fee

Prices are from Notice 123, price list effective 4 Oct 2026.

Certificate of Mailing: the receipt USPS designed for this

The mailing standards say Certificates of Mailing "provide evidence that individual mailpieces have been presented to the USPS for mailing." The USPS help article puts it more simply: it "provides evidence that you sent an item when you say you did."

How it works, from the standards:

• You fill it in. The form "must be completed by the mailer and all entries must be typed or printed in ink." It "must show the names and addresses of the sender and addressee(s) and may show the amount of postage paid."
• You present it with the mail. Certificates "may be presented only at the time of mailing."
• The clerk dates it. Each form "is postmarked (round-dated) at the time of mailing; the form(s) are then returned to the mailer and become the mailer's receipt."
• One or two pieces use PS Form 3817. Three or more go on the firm sheet, PS Form 3665, at $0.75 per piece listed.
• A rural carrier can do it. For PS Form 3817 the standards let you give the mail and the fee to the rural carrier, who gets the certificate postmarked at the Post Office on the day of mailing and brings it back "on the next trip."

And its limits, also from USPS:

• No delivery record. "Certificates of Mailing do not provide a record of delivery." The help article adds: "No signature or receipt is obtained when Certificate of Mailing items are delivered to the recipient."
• No copy at USPS. "The Postal Service does not retain copies of either form." If you lose the certificate, there is nothing to ask for.
• No insurance, no tracking. It is a receipt, not a service that follows the letter.

It can be bought with First-Class Mail and Priority Mail, among other classes.

Certified Mail: a mailing receipt plus a delivery record

Certified Mail "provides the sender with a mailing receipt and, upon request, electronic verification that an article was delivered or that a delivery attempt was made." So it covers both ends: the receipt for the day it went, and the delivery status for the day it arrived.

The detail that matters for proof of mailing is who dated the receipt. The standards describe two cases:

• Presented to a clerk: "attach the Form 3800 with the completed receipt to the address side of the article and present the article to the USPS employee, who then round-dates the receipt (and receipts the time, if requested) to show when the article was accepted."
• Dropped in a mailbox: "attach the 'Certified Mail' sticker to the address side of the article, detach the receipt, mark the receipt to show the date, and mail the article." That date is one you wrote yourself.

The steps and the forms are in our guide to sending certified mail. If you also want the signature sent back to you, that is a return receipt.

Registered Mail: the most documented, and the most expensive

USPS calls Registered Mail "the most secure service that the USPS offers. It incorporates a system of receipts to monitor the movement of the mail from the point of acceptance to delivery." Like Certified Mail it gives the sender a mailing receipt. The fee starts at $20.90 for an article declared to have no value and rises with the declared value. It is built around security for valuable items, and the two options above cost less.

A postmark at the counter: dated, but it leaves with the envelope

Since 24 Dec 2025 the mailing standards have a section that defines postmarks (DMM 608.11). It says a customer "may request, for no additional fee, a manual (local) postmark at any Post Office, station, or branch when tendering their mailpiece," and that because this postmark "is applied upon acceptance at the retail counter, the date on that postmark aligns with the date on which the Postal Service first accepted possession of the mailpiece."

The same section says the label a clerk prints when you pay for postage at the counter, the Postage Validation Imprint, carries the acceptance date too.

Two things to weigh:

• The postmark is on the envelope. The envelope goes to the recipient. You do not keep it, so it helps only where the recipient is the one who checks the date, for example an office that counts the postmark.
• A postmark applied by a machine is a different thing. Its date is "the date of the first automated-processing operation performed on that mailpiece," which USPS says "may be later than the date that the mailpiece was first accepted." Our page on the postmark rule goes through that.

What does not count as proof of mailing

The same DMM section is blunt about three things people rely on.

Postage you printed yourself. "Pre-printed labels applied by the customer prior to mailing (e.g., postage printed from Self-Service Kiosks (SSK), Click-N-Ship online postage, and meter strips) show merely that a customer has purchased postage and the date on which the postage was printed; they do not in themselves demonstrate that the Postal Service accepted the mailpiece, or the date on which any such acceptance occurred."

Scan data and barcodes. Markings and scans made during processing "indicate possession of a mailpiece; however, they do not constitute evidence of the date when the Postal Service first accepted possession of a mailpiece."

The absence of a postmark. It proves nothing either way: "the absence of a postmark does not imply that the Postal Service did not accept custody of a mailpiece, because the Postal Service does not postmark all mail in the ordinary course of operations."

A photo of the envelope at the mailbox, or your own note of the date, is your word. It is not a record made by USPS.

Proof of mailing is not proof of delivery

	Proof of mailing	Proof of delivery
The question it answers	Did you send it, and when?	Did it arrive, when, and who took it?
USPS records	Certificate of Mailing; Certified or Registered Mail receipt	Delivery status of Certified or Registered Mail; return receipt with the signature
Who keeps it	You. USPS keeps no copy of a Certificate of Mailing	USPS keeps the delivery record of Certified Mail

Which one you need depends on the rule you are working under. Some rules count the day you mailed. Others count the day the other side received. Read the rule, or ask the office that will apply it.

One rule that names its proof: federal tax filings

Most rules leave the kind of proof open. The IRS regulation on timely mailing does not, and it is a useful example of why the type of receipt matters.

26 CFR 301.7502-1 says that if a document is sent by U.S. certified mail "and the sender's receipt is postmarked by the postal employee to whom the document or payment is presented, the date of the U.S. postmark on the receipt is treated as the postmark date of the document or payment." For registered mail, "the date of registration" is treated as the postmark date.

On proving that a document was delivered at all, the regulation says proof of proper use of registered or certified mail, or of a designated private delivery service, are with direct proof of delivery "the exclusive means to establish prima facie evidence of delivery," and adds: "No other evidence of a postmark or of mailing will be prima facie evidence of delivery or raise a presumption that the document was delivered."

The regulation names registered mail, certified mail and designated private delivery services. It does not name a Certificate of Mailing. We read the regulation on 13 Nov 2026. This is a report of its text, not tax advice.

What you get from Certisent, and what you do not

A Certified Mail letter sent through Certisent has a USPS tracking number and a USPS delivery record. We also give you an evidence pack: one PDF with a summary, a copy of the pages we printed with their fingerprint, the time and place of the first USPS scan, the tracking history and, once USPS provides it, the electronic return receipt. We email you at every step on the way. The price is $14.99 for a letter of up to the included pages. Every Certisent letter goes by Certified Mail; we do not send untracked mail.

Be clear about what that PDF is: a record you can keep and share.

• It is Certisent's record, not a USPS form. It is not a Certificate of Mailing and it is not a PS Form 3800 receipt round-dated by a postal employee.
• If your deadline turns on a clerk's postmark, go to the counter. The federal tax rule above is one such case. Mail it yourself and have the receipt postmarked.
• No date promise. We cannot promise a delivery date or a postmark date. If your letter has a deadline, send it early.

What the service gives you is a dated trail and a USPS delivery record for a letter you did not have to carry to the counter.

This page is general information about postal services. It is not legal or tax advice.