Mailing Terminology

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When the Post Office and mail houses talk about mail and mailing requirements, knowing the following terms will help you better understand and speak the language.


Address Block— The space required for addressing and barcode required for Automation postage discounts.

Ancillary Service — Forwarding, Return or Address Correction service included within a mail class. Depending on the mail class, these services are performed at a nominal charge or at no additional charge, if the service is actually provided.

Aspect Ratio — The dimension of a mail piece expressed as a ratio of length divided by height. An aspect ratio between 1.3 and 2.5 is required for automation compatibility.

Automation Compatible Mail — Mail that can be scanned and processed by automated mail processing equipment such as a barcode sorter.

Barcode Clear Zone — A rectangular area in the lower right part of a letter-size piece that must be kept free of printing and symbols, except for the barcode itself.

Bulk Mail — The term is generally used to describe presorting mail including Presorted First-Class Mail and Standard Mail.

Business Reply Envelope — An envelope used by mailers for their customers to mail back, with the postage paid by the mailer only on the envelopes actually returned. A Business Reply Mail (BRM) permit is required.

CASS — Coding Accuracy Support System: A service that improves the accuracy of matching to delivery point codes, ZIP+4 codes, 5 digit ZIP codes, and carrier route codes on mail pieces. CASS sets a standard to measure the quality of address matching software and to diagnose and correct software problems. Any mailing claimed at an automation postage rate is required to be produced from address lists properly matched and coded with CASS-certified address matching methods.

Endorsement — An authorized marking on a mail piece that shows handling instructions, a service, or a request for an ancillary service.

Carrier Route Presort Mail — Mail sorted by carrier route to qualify for discount postage rates. The mail requires no primary or secondary distribution.

Destination Entry Discount — A postage discount for depositing mail at specific postal facilities that are closer to the final destination of the mail.

Flat-Size — A mail piece that exceeds 11-1/2" in length, 6-1/8" high, 1/4" thick, but does not exceed the maximum dimension of 15" long, 12" high and 3/4" thick.

Indicia — Imprinted designation on mail that denotes postage payment (e.g., permit imprint).

Letter-Size — Length: min. 5 ” - max. 11-1/2", Height: min. 3-1/2" - max. 6-1/8", Thickness: min. 0.007" - max. 1/4"

Mailing Permit — Permission to mail at bulk (presorted) rates.

NCOA — National Change of Address: An address correction service that matches mailing lists against change-of-address information for the US. This electronic process returns your database with the moved addresses flagged for correction and is used to comply with the USPS regulation required for mailing First Class at discounted postage rates. An address list must be updated every 6 months or 180 days. There is usually a charge for this service.

Non-machineable — The inability of a mail piece to be sorted on mail processing equipment because of size, shape, content, or address legibility. Such mail must be processed manually and could be subject to a surcharge.

Non-Profit Class — A subcategory of Standard Class. A mailer must apply with the USPS for the ability to mail at Non-Profit postage rates.

Permit Imprint — A printed indicia, instead of an adhesive postage stamp or metered postage, which shows postage prepayment by an authorized mailer. A permit requires an annual fee and mailings must be made at least once a year.

Postage Statement — Documentation provided by a mailer to the USPS that reports the volume of mail being presented and the postage payable or affixed, and certifies that the mail meets the applicable eligibility standards for the rate claimed.

Post Card — Length: min. 5" - max. 6", Height: min. 3-1/2" - max. 4-1/4", Thickness: min. 0.007" - max. 0.016"

Postnet Barcode — A series of vertical bars and spaces, which represent any numerical series, most often a correct Zip code for the delivery address on a mail piece. This is required for Automation postage discounts.

Presort First Class — A non-automation rate category for a mailing that consists of at least 500 addressed mail pieces and is sorted and prepared according to USPS standards. The postage discounts are determined by the quantity of pieces with the same 5 digit zip codes or 3 digit zip codes, etc. This mail does not bear a barcode.

Presorted Mail — A form of mail preparation, required to bypass certain postal operations, in which the mailer groups pieces in a mailing by ZIP Code or by carrier route or carrier walk sequence (or other USPS-recommended separation).

Presorted Rates — A discounted postage rate. In exchange for this lower postage rate, mailers must sort their mail into containers based on the ZIP Code destinations on the mail.

Presorted Standard Class — A presorted Standard Class mailing requires a minimum of 200 pieces. The mailing consists of addresses that have been sorted according to zip codes. The postage discounts are determined by the quantity of pieces with the same 5 digit zip codes or 3 digit zip codes, etc. For Automation postage discounts the mail piece must meet size, addressing space and tabbing requirements.

Purge — The process of eliminating duplicates and/or unwanted names from one or more lists.

Sectional Center Facility (SCF) — A postal facility that serves as the processing and distribution center for Post Offices in a designated geographic area as defined by the first three digits of the ZIP Codes of those offices. Some SCFs serve more than one 3-digit ZIP Code range.

Single-Piece Rate — The undiscounted or full postage rate available for individual pieces of Express Mail, First Class Mail, Priority Mail and Package Services.

Tabs or Wafer Seals — Self adhesive paper or plastic spheres used to secure the open edge of a non-enveloped letter-size mail piece to prevent jamming in high-speed processing equipment. Tabs are required when this type of mail piece is submitted at automation postage rates. The design and construction of the mail piece plays an important part in determining the number and placement of the tabs required to mail at automation discount rates.