Publication 430 - All About Merlin
June 2005
PSN 7610-08-000-1461


MERLINTM— an acronym for the Mail Evaluation Readability Lookup INstrument — is a tool that the U. S. Postal Service® uses to assist with the acceptance of discount-rate mailings.

The Postal ServiceTM offers discounts for mailings that meet certain address, barcode, and sortation standards so that the mailing can bypass certain processing steps to expedite the mailing process. These special discounts are called "workshare" discounts. MERLIN allows the Postal Service to verify overall mail quality and apply appropriate customer discounts.

Benefits of MERLIN

MERLIN helps you qualify for automation discounts and meet certain mail quality standards.

MERLIN helps improve the quality of your mail production process and facilitates qualification for reduced postage rates.

MERLIN provides a variety of reports that can help you improve overall mailpiece design and quality.

Using MERLIN to improve mail quality can result in:

• Reduced mail production costs.

• Accurate application of discount rates.

• Increased consistency of mail delivery.

Your mail and MERLIN

When you present your mailing for acceptance, the Postal Service may select it for processing on MERLIN. MERLIN measures your mailing against the following standards noted in the Mailing Standards of the United States Postal Service, Domestic Mail Manual (DMM®):

• The readability of the barcode.

• The improper use of "9999" or "0000" ZIP+4® codes.

• The proper make-up (presort) of the mail.

• The proper number of pieces (for permit imprint mail).

• The accuracy of applied meter postage for First-Class Mail® service.

Additionally, MERLIN checks the following:

• Accuracy of the mailing address.

• Compliance with mailpiece characteristic standards including height, weight, thickness, and aspect ratio.

• Meter identification and dates.

• Endorsements.

• Rate markings.

For additional information on the verifications MERLIN can perform, visit the MERLIN Web site at

Mail types analyzed by MERLIN

MERLIN may process letter and flat-size mailings that fall within the following dimensions:

• Maximum Length - 12 inches.

• Maximum Height - 15 inches.

• Maximum Thickness - .75 inch.

• Maximum Weight - 16 ounces.

Quality improvement reports

When your mail is processed on MERLIN, you will receive a Summary Verification Report listing the results of each verification performed. If any quality issues are detected, the Postal Service provides additional reports identifying areas needing improvement to meet DMM standards. Be sure to ask the acceptance clerk for copies of these reports in order to monitor your mail quality. You can access sample reports and descriptions on the MERLIN Web site at

What if you disagree with the verification results?

If your mailing has not passed MERLIN and you question the results, you can request a second-level review with U.S. Postal Service acceptance personnel.

A mailpiece design analyst (MDA), business mail entry supervisor, or other designated USPS® employee completes the second-level review. For barcode readability errors, you may request that the second-level review be performed specifically by an MDA (although another designated USPS employee may conduct the second-level review of other errors, if any). The MDA reviews live mailpieces that were identified with quality issues as quickly as possible; however, there may be a delay if the MDA is not readily available at your acceptance site.

If you are unable to resolve the disagreement at the second-level review, you may appeal to the next level as follows:

• Although Presort verification, First-Class Meter mail, and piece-count differences are usually resolved at the time of mailing, you may make an appeal through a general appeal process. You may send a written appeal to the postmaster within 30 days. The appeal is forwarded to the Pricing and Classification Service Center for review and final agency decision (DMM 607.2).

• For barcode readability failures, you may request that the Postal Service send the sample pieces tested by MERLIN to a dedicated appeals site where the samples are retested on the MERLIN appeal machine. If the appeal results are lower than the initial results, the Postal Service may charge additional postage (above the original assessments). If the appeal results are higher than the initial results, the Postal Service may provide a refund.

• For barcode digit string "9999" failures, you may request that the Postal Service send the addresses of the pieces with the "9999" ZIP+4 codes found in the sample to the National Customer Support Center (NCSC) for validation. The origin acceptance site will notify you of the results from the NCSC.

Resources for improving mail quality

The MERLIN Web site

The Postal Service has recently redesigned and updated the MERLIN Web site at The new site provides important information about the MERLIN verification process and, more importantly, tips on how to improve your mail quality and where to get help with your mailpiece design questions.

Mailpiece Design Analysts

Mailpiece design analysts (MDAs) are Postal Service employees who are specially trained to answer your questions regarding mailpiece design. MDAs can assist you in several ways:

• Review mailpiece designs to verify that they meet DMM standards for discounted rates.

• Arrange for testing a sample of 25-50 pieces on MERLIN to identify quality issues before a full print run is completed.

• Provide technical assistance with barcoding and addressing standards.

You can locate your local MDA on the MERLIN Web site at; click on Get Help with MERLIN and then on Find a Mailpiece Design Analyst (MDA).

Manager of Business Mail Entry

The manager of business mail entry can answer any questions about the MERLIN program or process and can assist you with your overall mail quality. You can locate your local manager of business mail entry on the MERLIN Web site at; click on Get Help with MERLIN and then on Locate a Business Mail Entry Unit (BMEU).

Business Services Network

If you have a managed account, you may also contact your Business Services Network (BSN) representative with questions that are not addressed through other means. You can locate your local BSN on the MERLIN Web site at; click on Get Help with MERLIN and then on Find a Business Services Network (BSN).

For additional help with any MERLIN issue, send an e-mail to A USPS representative will respond directly to your message.

Publication 430, June 2005
PSN 7610-08-000-1461