Notes about MERLIN

MERLIN (Mailing Evaluation Readability Lookup Instrument) automates mail verification procedures that were previously done manually. It verifies adherence to mailing standards for:

• Letter and flat-size mail
• Automated and non-automated mail
• First-class, standard, nonprofit, and periodical mail

The domestic mail standards have not changed.

A MERLIN test can take 30 minutes to more than three hours. The USPS directive is to not delay the mail.
Jobs are randomly selected for MERLIN verification. The USPS goals are to verify:

• 17% of presorted mail
• every mailing over 10,000 pieces
• one in six mailings under 10,000 pieces

Sample sizes for testing:

• Letter-size mailings over 10,000 pieces: 1,000
• Letter-size mailings under 10,000 pieces: 500
• Flat-size mailings: 500
• Letter- or flat-size mailings under 500 pieces: all pieces

MERLIN verifies:

• Presort/mail make-up
• Weight/piece count
• Barcode readability
• Tray label accuracy
• Meter identification and date
• Address/barcode accuracy
• Mail piece dimensions
• Carrier routes
• Line-of-travel
• Walk sequence

To avoid MERLIN “penalties”:

• 90% of letter samples must pass (if a letter mailing is 80-89% compliant, there is a partial assessment)
• 80% of flat samples must pass

If a mailing fails MERLIN’s test:

• Higher mailing costs must be paid—at the rate the mailing does qualify for
• You can appeal barcode readability results through a special appeal process with USPS’s Chicago facility
• Other appeals go through the traditional (local) appeal process

MERLIN will reject mail for the following barcode errors:

• Bar too tall
• Bar too short
• Bar too wide
• Bar too narrow
• Barcode position problem
• Void (area without ink)
• Extraneous ink present
• Baseline shift
• Bar tilt
• Pattern skew
• Bar pitch too close
• Bar pitch too far
• Low background reflectance
• Barcode clearance position
• Connected bars
• Barcode will not decode
• Invalid delivery point barcode
• Bar space too close
• Bar space too far

Potential design problems with MERLIN implementation:

• Glossy stock—barcodes can smear
• Porous papers like newsprint and textures—barcodes can bleed
• Colored or fluorescent paper and screens or images in address area—inadequate contrast between paper and barcode (for readability)
• Flecked paper—MERLIN can read flecks as “extraneous ink present”

Preventive design recommendations:

• Uncoated, nonporous papers are best for ink-jetting addresses clearly
• Address areas should be knocked out for varnishes, aqueous, or UV coatings
• Folds and trims must be consistent on all pieces for uniform addressing alignment
• Address label area must be proper size—4" X 2" is ideal; 3" X 1" is the minimum
• Address label position must fall within “OCR Read Area” —see USPS template #67
• Ensure proper alignment of address in window envelopes (tap test)