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Certified Mail, Certificate of Mailing, or IMb Barcode: What Does Each Service Provide?

(Updated August 14, 2020)

By: Peter Wade
Decision Validation, LLC
Tel: (305) 420-5907
Email Mr. Wade

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The United States Postal Service offers three services which document that articles have been placed in the mail at a certain place on a certain date; Certified Mail, a Certificate of Mailing, and a 65-digit Intelligent Mail Barcode (IMb).


The USPS defines Certified Mail as: A Special Service that provides the sender with a mailing receipt and, upon request, electronic verification that an article was delivered or that a delivery attempt was made. A fee is charged for the service in addition to postage. Customers can retrieve the delivery status at; through a 1-800 telephone number; or by bulk electronic file transfer for mailers who provide an electronic manifest to USPS. No insurance coverage is provided with the service. USPS maintains a record of delivery (which includes the recipient's signature) for a specified period of time.

Each Certified Mail letter has a unique serial number and corresponding barcode. A Certified Mail letter does not have to be presented to a USPS employee for confirmation that it has entered the U. S. Mail.

The mailer may deposit properly prepared Certified Mail letters in any authorized mail receptacle without presenting the letter to a USPS employee for examination and verification.

Each Certified Mail form has a barcode which pertains to that unique receipt. Services such as allow the mailer to prepare Certified letters on their printer. This process also provides a unique Certified Letter number and bar code.

During mail processing operations, when this barcode is first read USPS scanners, the return address and addressee of the Certified Mail letter are recorded in the USPS Automated Tracking System.

The Automated Tracking System provides a record of where the particular Certified Mail letter is each time it moves through the mail stream. The system also provides a facsimile of the signature of the person who signs for the letter when it is received.

If the Certified mail letter is not delivered for any reason (unclaimed, refused, no forwarding address on file, deceased, etc.), the Automated Tracking System provides information as to each place the letter has traveled and, if returned to sender, the reason the Certified Mail letter is being returned. If the Certified Mail letter is forwarded to a new address, the Automated Tracking System provides that information too.

Records of delivery or return of Certified Mail items are retained by the USPS for two years. These records are available to the general public. The easiest way to trace a Certified Mail letter is to go to the USPS website and enter the Certified Mail number in the Track and Confirm section. If the Certified Mail letter was delivered, a facsimile of the signed receipt will be available online.

Since neither the sender nor the addressee can alter the USPS Automated Tracking records, those records cannot be manipulated by a party in interest who might claim receipt or non-receipt for their own interests.


The USPS defines a Certificate of Mailing as: A Special Service that provides evidence that mail was presented to USPS for mailing. Certificate of Mailing service does not provide a record of delivery.

The form must be presented to a USPS employee for examination at the time the letter is placed in the mail. The USPS employee examines the form, assures that proper fees are paid (at this writing, $1.40 for one letter, $8.25 for six to 1000 letters; and $1.03 per each additional 1000 letters).

Unlike other special services where the amount paid for both postage and related fees is placed on the individual letter, with a Certificate of Mailing the postage for the appropriate fees is affixed to the Certificate of Mailing form, the USPS employee stamps the form with an official stamp which indicates the location and date the letter(s) was mailed.

The USPS employee returns the validated receipt to the mailer. Unlike other Special Services, the USPS does not maintain a copy of the Certificate of Mailing. The USPS does not track these letters through the mail stream. The USPS does not verify that the addresses on those letters are complete or accurate, nor does it keep a record of whether any of those letters were returned to sender.

A Certificate of Mailing is NOT proof that a letter was received by the addressee. Since the only record of the mailing is in the possession of a party of interest, the addressee cannot rely upon the business records of a disinterested third party (USPS) in contesting the receipt of such a letter.

Many mailers are aware of the defect inherent in this form of mailing documentation. The Internal Revenue Service, for instance, recognizes this problem. The IRS asserts that: "A Certificate of Mailing with a timely date is not as evidence to them that a letter was timely sent to the IRS." A Certificate of Mailing and a letter to the IRS both stamped at the same time on the same day at the same place may be considered proof.


Common uses of Certificates of Mailing include documentation that an article was mailed on a timely basis. Bulk advertising mailers, for instance, might request a Certificate of Mailing as evidence to their client that the requested number of advertisements were mailed on the requested mailing date; or a company submitting a competitive bid for a contract might obtain a Certificate of Mailing to establish the date that a bid was mailed in case the postmark might be illegible. In both of these hypothetical situations, the addressee must have the envelope and the sender must have the corresponding Certificate of Mailing.

USPS Warns Mailers that a Certificate of Mailing Does Not Provide Evidence that a Letter Was Mailed to a Particular Address

Two USPS forms must be presented to the USPS when requesting a Certificate of Mailing: PS Form 3606-D "Certificate of Bulk Mailing -Domestic, and PS Form 3665 "Certificate of Mailing -Firm"
Page one of Form 3606-D cautions the mailer: "This Certificate does not provide evidence that a particular piece was mailed to a particular address." Page two of form 3606-D clearly states: "Certificate of Bulk Mailing - Domestic service does not provide a record of delivery, and the Postal Service does not retain any copies of PS Form 3606-D. The mailer cannot use PS Form 3606-D as a certificate of mailing for individual mailpieces or itemized lists".

Additionally, there is a caution on page two of PS Form 3665, Certificate of Mailing - Firm: "The forms become the mailer's only receipt (the Postal service does not retain a copy)".

While the delivery status of every Certified Mail letter is recorded, the intensity of the verification of a group of letters listed on a Certificate of Mailing depends upon the individual mailer's history of preparing accurate documentation for mailings. With a mailer who mails at low volume on an infrequent basis, the verification can be as high as 10%, or 30, of 300 letters. For more frequent mailers of high volume the verification can be 100 of 100,000 letters mailed - or .001%. USPS instructions call for verifying as few as 1of 5 mailings per week for high volume mailers with a good accuracy history.


The USPS describes Intelligent Mail Barcode Tracing as follows:

"IMb Tracing is a service that provides real-time tracking information for your automation-compatible letters and flats, giving advance notice for both incoming and outgoing mail.

  • Destination IMb Tracing service (for outgoing mail) gives you advance information about when your mailpieces will reach their destination.
  • Origin IMb Tracing service (for incoming mail) lets you anticipate when customers' checks, replies, or orders are on the way back to you.

How does IMb Tracing help my business?

For outgoing mail:

  • Obtain near-real-time notification when your mail receives its last processing scan.
  • Identify mail delivery trends and ensure delivery is within in-home dates.
  • Know when your message reached your audience so you can synchronize multichannel marketing.
  • Enable fulfillment, staffing, and inventory planning based on mail delivery.

For incoming mail:

  • Obtain near-real-time notification when your return mail enters the mailstream.
  • Know when return items are on the way so you can better manage your supply chain.
  • Manage cash flow and accounts receivable more effectively.
  • Evaluate the success of advertising campaigns in near real-time."

So, business mailers meeting all the requirements to use the 65 digit IMb barcode have a complete USPS record which contains much of the information that Certified Mail tracking provides; however, IMb tracking ends at the point where the article has been provided to the carrier, or clerk for delivery.

IMb tracking unlike Certified mail,  does not provide information as to whether the addressee had moved, died, or refused delivery of the article.

Pricing Factors

The fee for mailing a Certified Letter is $3.55. That fee per letter is the same whether the mailer is sending one Certified Letter or 1,000 Certified Letters at the same time. The fee for mailing letters using a Certificate of Mailing is $1.50 for one letter, but only $8.75 for up to 1000 letters and additional $1.09 for every additional 1000 letters.

Therefore, it would cost a mailer $3,550.00 in fees to send 1,000 Certified Letters. To send 1, 000 letters under a single Certificate of Mailing would cost the same mailer $8.75 in fees.

The USPS is required by law to set costs which reflect their expenses for each service they provide. Each Certified Mail letter must be accounted for. Letters mailed under a Certificate of Mailing are subject to random verification. Each letter listed on Form 3665 doesn't have to be located and checked against the manifest. The vast difference in postage charged for Certified Mail versus a Certificate of Mailing reflects the assurance the U.S. Postal Service provides as to whether an article of mail was delivered.

While there is no separate fee for IMb tracing service, mailers must comply with a number of mail conformance requirements in order to obtain this tracing service. There are significant fees involved in adhering to those requirements.

Good Faith Notice

In 2014, the Postal Regulatory Commission commissioned marketing firm NuStats to conduct a "Household Diary Study". One area researched in the study was number of mail pieces received per household per week. A middle income family was found to receive 20 pieces of mail per week, or 80 pieces of mail per month.

The study further stated that middle income households which receive 80 pieces of mail per month, only 12% of those households usually read all their mail, 37% read some of their mail and 33% usually scan their mail. Eighteen percent of those households -or roughly one household in five- usually don't read their mail.

In an effort to get the addressee to at least open the envelope and scan its contents, corporate mailers often place notices on the envelopes such as: "Notice of Cancelation", "personal and confidential", "renewal", "priority document", "warranty expiring", "valid only until (date)", etc.

In determining a mailer's good faith attempt to notify holders of canceled policies, a comparison of the endorsements on the mailing envelope is recommended.

Do envelopes used to invoice customers bear any related information on the front of the envelope? For instance, "Renewal Notice", "Payment Due", or "Invoice Enclosed". If so, do policy cancelation letters contain any related information on the front of the envelope? For instance, "Cancelation Notice" or "Final Notice".

Another indication of good faith notice is whether there is any reconciliation of mailing manifests to identify letters returned to them as undeliverable.

The USPS requires a 99% accuracy rate from mailers using IMb. Therefore 50 undeliverable letters in a mailing of 5000 notices means that up to 50 insureds have been exposed to hundreds of thousands of dollars of loss and might not realize it.

There is no postal regulation requiring mailers to correct errors and re-mail notices. If there are re-notification procedures for invoices; are there such re-notification protocols for cancelations?

Even the USPS Can Not Use a Certificate of Mailing as Proof of Delivery

The Postal Regulatory Commission promulgates the rules in Title 39 US Code. They are an independent agency which oversees USPS rates, services, etc. The PRC recognizes that mere delivery of a notice does not prove that it came to the attention of the concerned party.
The USPS does not recognize a Certificate of Mailing as evidence that a communication has been received by the addressee. The USPS is regulated by Title 39 of the United States Code. That code specifies legal notice delivery methods for the USPS. For example:

Title 39 US Code Manner of service.
Service of process on the Authorized Agent or his designee may be made in person or by certified or registered mail, with return receipt requested, at the address of the Authorized Agent. Service may also be made on the Authorized Agent by means of any private delivery service pursuant to its authority for the private carriage of letters under an exception to the Private Express Statutes, 39 U.S.C. 601-606, provided that the private delivery organization issues a receipt bearing the name and address of both the addressee and sender, as well as the date of delivery and the signature of the receiving agent.

Peter Wade, was employed by the USPS for 32 years. He served in supervisory and administrative positions with the U S Postal Inspection Service in New York, Los Angeles, Philadelphia, San Francisco, and San Juan. He was also the Postmaster of San Juan PR and Field Division General Manager for the USPS Caribbean District responsible for providing postal services to 4 million customers and supervising 3000 USPS employees.

Mr. Wade has been a consultant and expert witness in postal related matters for 19 years. He has advised on numerous postal matters, including the merging of two independent postal services in Argentina. He has offered efficiency improvement and security advice to many business clients of the USPS. He has provided testimony in both civil and criminal proceedings in postal related litigation.

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