# Mailpiece design: size, shape and machinability A mailpiece's length, height, thickness and weight make it a letter, a flat or a parcel, USPS's mail processing categories.[^1] A letter is at most 11-1/2 by 6-1/8 inches and 1/4 inch thick, a flat 15 by 12 inches and 3/4 inch thick.[^2][^3] A piece that machines can't sort is nonmachinable and may pay a surcharge.[^4] Updated November 5, 2026. 54 sources. ## Questions ### What is the minimum letter size to mail? A letter must be at least 3-1/2 inches high, 5 inches long and 0.007 inch thick to be mailable.[^5] A letter more than 6 inches long or 4-1/4 inches high must be at least 0.009 inch thick.[^6] A single-piece First-Class Mail letter thinner than that pays the nonmachinable surcharge.[^6][^7] For [automation](https://postalref.com/guides/mail-classes.md#prices) compatibility, so automated equipment can scan and process it, a letter's aspect ratio, length divided by height, must be between 1.3 and 2.5.[^8][^9] A single-piece First-Class Mail letter outside that range still mails, with the nonmachinable surcharge.[^9][^7][^6] ### What size envelope requires extra postage? A single-piece First-Class Mail letter pays the [nonmachinable surcharge](#machinability) when it has a nonmachinable trait, such as an aspect ratio under 1.3 or over 2.5.[^7][^6] A letter over 3.5 ounces pays flat prices, as does an envelope over a letter's size up to 15 by 12 inches and 3/4 inch thick.[^6][^3][^10] A larger piece is a parcel, and a large envelope that is rigid, nonrectangular or not uniformly thick pays parcel prices.[^11][^12] As of October 4, 2026, the surcharge is $0.49, a 1-ounce stamped letter costs $0.82, and a 1-ounce large envelope costs $1.69.[^12] ### What size envelopes can be mailed? An envelope mails as a letter up to 11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick and 3.5 ounces.[^2][^13] A larger envelope is a flat, up to 15 inches long, 12 inches high and 3/4 inch thick, and it must be flexible.[^3] Mail that is neither a letter nor a flat is a parcel.[^11] ### How much is the USPS nonmachinable surcharge? As of October 4, 2026, the nonmachinable surcharge is $0.49 a piece, added to a single-piece First-Class Mail letter with one or more [nonmachinable traits](#machinability).[^12][^7] Pieces mailed at the card price don't pay it.[^7] A shortpaid nonmachinable First-Class Mail letter goes back to the sender for more postage.[^14] ### What size postcards can be mailed? A card mails at the First-Class Mail postcard price up to 4-1/4 inches high, 6 inches long and 0.016 inch thick.[^15] Like any piece up to 1/4 inch thick, it must be at least 3-1/2 inches high and 5 inches long.[^5] A larger postcard pays First-Class Mail letter postage instead.[^16] ### What envelope size can I mail with one stamp? One Forever stamp pays the First-Class Mail single-piece price for a 1-ounce letter.[^14] A letter is at most 11-1/2 inches long, 6-1/8 inches high and 1/4 inch thick.[^2] USPS also sells Forever stamps worth the additional-ounce price and the nonmachinable surcharge.[^14] ### What is a TED-C letter? A TED-C letter is a letter-size piece with a die-cut that extends past its conventional trailing edge, its left edge.[^17][^18] Under [Alternative Designs](https://postalref.com/products/alternative-designs.md), these non-rectangular letters mail at [automation letter prices](https://postalref.com/guides/mail-classes.md#prices).[^19] Only [Full-Service](https://postalref.com/guides/full-service.md) First-Class Mail and USPS Marketing Mail letters with an Intelligent Mail barcode in the address block qualify.[^17] ### Is pre-approval by USPS required to mail TED-C letters? No: since February 1, 2023, mailers need no pre-approval from the Pricing and Classification Service Center to mail TED-C letters.[^17] They may check a piece with the TED-C Letters Template.[^17] USPS encourages mailers to send TED-C designs to a Mailpiece Design Analyst for review.[^17] ## How it fits together A mailpiece's dimensions, physical characteristics and weight set its mail processing category.[^1] A letter is no larger than 11-1/2 by 6-1/8 inches and 1/4 inch thick.[^2] A flat is larger than a letter in one dimension, up to 15 by 12 inches and 3/4 inch thick.[^3] Mail that is neither is a parcel, which USPS sorts as machinable or nonstandard.[^11][^20] The irregular and outside parcels were earlier categories: USPS retired the irregular parcel, and the outside parcel became the nonstandard parcel.[^21][^22] Within each shape, a machinable piece fits the specifications and tolerances of USPS's mail processing equipment.[^23] A nonmachinable piece is processed by hand and may pay a surcharge or a higher price.[^4] [Automation prices](https://postalref.com/guides/mail-classes.md#prices) go to mail that is presorted, prebarcoded and readable by automated equipment.[^24] They are generally lower than single-piece and nonautomation presorted prices.[^24] The OCR read area is a band near the bottom of the address side.[^25] A letter keeps its lower right corner, the barcode clear zone, free for the barcode.[^26] Its [Intelligent Mail barcode](https://postalref.com/products/intelligent-mail-barcode.md) goes in the address block or that clear zone.[^27] A package's [shipping label](https://postalref.com/guides/package-labels.md) goes fully on its address side.[^28] [Alternative Designs](https://postalref.com/products/alternative-designs.md) lets non-rectangular TED-C letters mail at automation letter prices.[^19] [Polywrap and Polywrap Manufacturers](https://postalref.com/products/polywrap-and-polywrap-manufacturers.md) lists the polywrap approved for automation-rate flats.[^29] Mailpiece Design Analysts, USPS employees trained in mailpiece design, answer questions about a design.[^30] ## Letters, flats and parcels Letter-size mail is the letters and cards that meet the minimum size standards and stay within its maximum dimensions.[^2] Its length is the side parallel to the address.[^9] A flat's length is its longest side, wherever the address is.[^31] | Shape | Height | Length | Thickness | Weight | | --- | --- | --- | --- | --- | | Card at the postcard price | 3-1/2 to 4-1/4 inches[^5][^15] | 5 to 6 inches[^5][^15] | 0.007 to 0.016 inch[^5][^15] | | | Letter | 3-1/2 to 6-1/8 inches[^5][^2] | 5 to 11-1/2 inches[^5][^2] | 0.007 to 1/4 inch[^5][^2] | Up to 3.5 ounces[^13] | | Flat | Up to 12 inches[^3] | Up to 15 inches[^3] | Up to 3/4 inch[^3] | | A letter more than 6 inches long or 4-1/4 inches high must be at least 0.009 inch thick.[^6] A single-piece First-Class Mail letter thinner than that pays the nonmachinable surcharge.[^6][^7] A First-Class Mail letter over 3.5 ounces pays flat prices.[^6] A card is a letter-size piece of cardstock without an envelope, and also the First-Class Mail price for one.[^32] A postcard pays card or letter postage, depending on its dimensions.[^16] A flat must be rectangular, with square corners or corners rounded to a radius of no more than 1/8 inch.[^3] It must also be flexible.[^3] It may be unwrapped, sleeved, wrapped or in an envelope.[^3] Flats claimed at automation prices have different minimum dimensions.[^3] A machinable parcel is the size, shape and weight to be sorted safely by machines such as a parcel sorting machine.[^23] A parcel that isn't machinable is nonstandard, such as one more than 22 inches long, 18 inches wide or 15 inches high.[^20] A parcel over 25 pounds is nonstandard too, as is a USPS Marketing Mail parcel under 3.5 ounces.[^20] Cylindrical tubes and rolls, cans, and wood or metal boxes are nonstandard parcels too.[^20] USPS called the nonstandard parcel the outside parcel until a DMM revision published January 17, 2016 renamed it the nonmachinable parcel.[^22] The nonmachinable parcel later became the nonstandard parcel.[^21] The irregular parcel, one that missed a machinable parcel's dimensions or minimum weight, is a retired category.[^33][^21] Packages of four products pay [nonstandard fees](https://postalref.com/guides/package-payment.md) past set lengths or volumes:[^34] - Priority Mail Express - Priority Mail - Parcel Select - USPS Ground Advantage - **letter-size mail**, also called Letter, LT, Letters including post cards: “A mail processing category that consists of letters and cards meeting minimum size standards and not exceeding the maximum letter-size mail dimensions of 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.”[^2] - **card**: “(1) A letter-size mailpiece of cardstock without an envelope, defined by its dimensions and physical construction. (2) A unique First-Class Mail price for such a mailpiece.”[^32] - **postcard**: “A commercially produced and sold rectangular card designed for writing and mailing without an envelope and requiring First-Class Mail card or letter postage, depending on the dimensions. Postcards generally show a photograph or illustration on one side.”[^16] - **Machinable Parcel**, also called MP: “A mailpiece that is of the correct size, shape, and weight to be safely sorted by mail processing machinery such as a parcel sorting machine.”[^23] - **Nonstandard Parcel**, also called IR: “A mail processing category for a mailpiece that exceeds the dimensions for machinable parcel or a high density item (other than a book or printed matter).”[^35] - **minimum size standard**: “The smallest dimensions permitted for all mailable matter or for a specific mail processing category or specific price. For mailability, all mailpieces must be at least 0.007 inch thick. For mailpieces 0.007 inch to 1/4 inch thick, the pieces must be at least 3-1/2 inches high and at least 5 inches long, except keys and identification devices.”[^5] - **flat-size mail**, also called FL, flat, large envelopes: “A mailpiece that exceeds one of the dimensions for letter-size mail (11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick) but that does not exceed the maximum dimension for the mail processing category (15 inches long, 12 inches high, 3/4 inch thick). Flat-size mail must be rectangular with four square corners or with finished corners that do not exceed a radius of 1/8 inch. Flat-size mail must also be flexible. Minimum dimensions are different for flat-size mail claimed at automation prices. Flat-size mail may be unwrapped, sleeved, wrapped, or enveloped.”[^3] ## Machinable and nonmachinable pieces A machinable piece can be sorted by USPS's equipment because its size, shape, configuration and weight fit the equipment's tolerances.[^23] A nonmachinable piece can't be, because of its size, shape, content or address legibility.[^4] It is processed by hand and may pay a surcharge or a higher price.[^4] An outside is a parcel or piece that must be handled by hand because of its size, weight, shape or contents.[^35] It is called an outside because it can't go in a sack or container.[^35] The outside parcel was something else: a mail processing category, and the old name of the [nonstandard parcel](#shapes).[^35][^22][^21] A nonmachinable single-piece First-Class Mail letter, stamped or metered, pays the nonmachinable surcharge, $0.49 a piece as of October 4, 2026.[^12][^7] Pieces mailed at the card price don't pay it.[^7] It applies to a letter-size piece with one or more of these nonmachinable traits:[^7][^6] - An aspect ratio, length divided by height, under 1.3 or over 2.5[^6] - A polybag, polywrap or other plastic cover, or an outside surface that isn't paper[^6] - Clasps, strings, buttons or similar closures[^6] - Contents such as pens, keys or coins that make its thickness uneven, or loose objects[^6] - Too rigid to bend easily around an 11-inch turn under 40 pounds of belt tension[^6] - Less than 0.009 inch thick when more than 6 inches long or 4-1/4 inches high[^6] - A delivery address parallel to its shorter side[^6] - A self-mailer or booklet not prepared to USPS's standards for them[^6] A [presorted](https://postalref.com/guides/presort.md) First-Class Mail letter that is nonmachinable pays a nonautomation nonmachinable price instead, one price per presort level.[^36] The aspect ratio is length divided by height: a postcard 5-1/2 inches long and 3-1/2 inches high has a ratio of 1.57.[^9] Automation compatibility takes a ratio between 1.3 and 2.5, inclusive.[^9] > Domestic Mail Manual (DMM) 201.1.1c provides that machinable letter and postcard priced mailpieces must be, “Rectangular, with four square corners and parallel opposite sides”.[^18] **Must.** A letter or postcard must be rectangular, with four square corners and parallel opposite sides, to be machinable. Until January 2012, Not Flat-Machinable was a separate price category for Standard Mail pieces of flat size or larger that missed the flats' uniformity or flexibility requirements.[^25][^37] Standard Mail was renamed USPS Marketing Mail on January 22, 2017.[^38] - **machinable**, also called machineable: “The physical capacity of a mailpiece to be sorted by mail processing equipment because its size, shape, configuration, and weight are within the specifications and tolerances of the equipment.”[^23] - **outside**: “A parcel or mailpiece that, because of size, weight, shape, or contents, must be handled manually. The mailpiece is called an outside because it cannot be placed into a sack or container.”[^35] - **nonmachinable**, also called non-machineable: “The incapacity of a mailpiece to be sorted on mail processing equipment because of size, shape, content, or address legibility. Such mail must be processed manually and may be subject to a surcharge or higher price.”[^4] - **aspect ratio**: “The dimension of a mailpiece expressed as a ratio of length (the direction parallel to the address) divided by height. For example, a postcard 5-1/2 inches long by 3-1/2 inches high has an aspect ratio of 1.57. An aspect ratio between 1.3 and 2.5, inclusive, is required for automation compatibility. For First-Class Mail letters, aspect ratio determines whether a nonmachinable surcharge applies.”[^9] ## The address side The OCR read area is a rectangle on the address side.[^25] It sits 1/2 inch in from the left and right edges, from 5/8 inch to 2-3/4 inches up from the bottom edge.[^25] On letter mail, the delivery address usually sits in the lower right.[^39] A piece that requests [ancillary services](https://postalref.com/guides/undeliverable-mail.md) needs a domestic return address.[^40] > First-Class Mail®, USPS Marketing Mail™ letters and flats, and Bound Printed Matter require the return address to be on the address side of the mailpiece in the upper left corner of the envelope or in the upper left corner of the addressing area.[^40] **Must.** On First-Class Mail, USPS Marketing Mail letters and flats, and Bound Printed Matter, the return address must go on the address side. It must sit in the upper left corner of the envelope or of the addressing area. The barcode clear zone is a rectangle in the lower right of a letter, kept free of printing and symbols except the barcode.[^26] It lets machines read a barcode there or print one.[^26] A barcode printed in it has its leftmost bar 3-1/2 to 4-1/4 inches from the right edge.[^41] It sits between 3/16 inch and 1/2 inch from the bottom edge.[^41] A window envelope has one or two openings on the address side, through which the address or barcode on the insert shows.[^42] On a flat, the Intelligent Mail barcode can go anywhere on the address side at least 1/8 inch from every edge.[^27] A First-Class Mail flat's delivery address can also go anywhere at least 1/8 inch from the edges, in the same read direction as the postage.[^31] On a package, the label goes fully on the address side, without wrapping over an edge or another label.[^28] On an unmarked box, the largest side should be treated as the address side.[^28] - **OCR read area**: “A rectangular area on the address side of the mailpiece that is 1/2 inch from the left and right edges of the mailpiece, 5/8 inch from the bottom edge, and 2-3/4 inches from the bottom edge.”[^25] - **address block**: “The area on a mailpiece containing the address to which USPS is to deliver a mailpiece.”[^43] - **delivery address**: “The location (destination) to which a mailpiece is delivered. Except for mail prepared with a detached address label, the piece must show the address of the addressee (intended recipient) on the side bearing postage stamps or postage indicia. On letter mail, the delivery address is usually placed in the lower right.”[^39] - **return address**: “A mailpiece element that is usually placed in the upper left corner of the mailpiece or address label to display the sender’s address. This address indicates where the sender wants the mail returned if it is undeliverable and where the sender will pay any fee due for that mail.”[^44] - **window envelope**: “An envelope with one or two openings (cutouts) on the address side through which a delivery address or barcode printed on the letter or insert placed in the envelope can be read. The openings must be covered with transparent material (such as glassine) for certain types of mail (such as Registered Mail).”[^42] - **barcode clear zone**: “A rectangular area in the lower right part of a letter-size mailpiece that must be kept free of printing and symbols, except for the barcode itself. This requirement allows automated processing machines to read or apply a barcode.”[^26] ## TED-C letters USPS and the mailing industry wrote the TED-C requirements, [Alternative Designs](https://postalref.com/products/alternative-designs.md), so that non-rectangular letters can mail at automation letter prices.[^19] A TED-C letter's die-cut extends past its conventional trailing edge, a line from the upper left corner to the lower left corner.[^17][^18] Only [Full-Service](https://postalref.com/guides/full-service.md) First-Class Mail and USPS Marketing Mail letters with an Intelligent Mail barcode in the address block qualify.[^17] A TED-C letter's maximum length, 10.5 inches, and maximum weight, 2.5 ounces, differ from the regular automation letter standards.[^17] Its die-cut extends no more than 5/8 inch from the conventional trailing edge.[^45] It must meet the minimum length without counting the die-cut.[^18] Its maximum length and maximum aspect ratio are measured with the die-cut, so a piece the die-cut makes longer than 10.5 inches pays the nonmachinable letter price.[^17][^18] Mailers may check a piece on the printed TED-C Letters Template, whose four zones stand for the sensors on USPS letter-sorting machines.[^17][^45] To use the template, a mailer places the piece's lower-left corner on it with the bottom edge on the line, then its upper-left corner with the top edge on the line, checking the die-cut at each.[^45] Some part of the die-cut must reach Zone B or Zone C.[^45] A die-cut may show in Informed Delivery's emails, but only one whose leftmost edge is in Zone C is sure to.[^45] A piece whose die-cut's leftmost edge is elsewhere may still mail, with no die-cut showing in Informed Delivery.[^45] - **TED-C letter**, also called TED-C (Trailing Edge Die-Cut) Letters, trailing edge die-cut (TED-C) letter-size mailpieces, TED-C mailpieces, Trailing Edge Die-Cut (TED-C) Automation Letters, TED-C, Trailing Edge Die-Cut: “TED-C mailpieces are letter-size pieces that have a die-cut that extends past the conventional trailing edge of the mailpiece.”[^17] - **conventional trailing edge**: “The conventional trailing edge is defined by a line drawn from the upper left corner to the lower left corner.”[^18] - **TED-C Letters Template**, also called TED-C Letter Template, Trailing Edge Die-Cut (Ted-C) Letters Template, LETTER MAIL TED-C INSPECTION TEMPLATE: “Template with instructions for Trailing Edge Die-Cut (Ted-C) Letters.”[^19] - **DIE-CUT MEASUREMENT ZONES**: “The four zones represent the sensors on the machines, or where the lights are placed.”[^45] ## Polywrap Polywrap is clear polythene film used to enclose mailpieces, including automation flat-size pieces.[^46] It is one kind of mailing wrapper, the cover that encloses a piece, with envelopes, sleeves and partial wrappers.[^47] From March 4, 2007, mailers who polywrapped these pieces had to use polywrap from USPS's approved list:[^29] - Automation-rate First-Class Mail flats - Automation-rate Periodicals flats - Automation-rate USPS Marketing Mail flats, then called Standard Mail[^38] - Barcoded Bound Printed Matter Any flat-size piece in polywrap must use polywrap from the list, unless it is mailed at saturation, high-density plus or high-density prices.[^20] A film joins the list after an approved laboratory tests it under USPS-T-3204, USPS's specification for testing polywrap film.[^48][^49][^50] The [Polywrap Manufacturer List](https://postalref.com/products/polywrap-and-polywrap-manufacturers.md) names the manufacturers and distributors of approved polywrap.[^29] - **polywrap**: “(1) Clear polythene film used to enclose mailpieces including automation flat-size pieces. (2) To enclose mailpieces with an automated process in which polythene is fed from reels under and around the pieces. The two edges are brought together and heat-sealed, and the top and bottom edges are crop-sealed to create the container.”[^46] - **mailing wrapper**: “An envelope, sleeve, partial wrapper, or polywrap used to enclose a mailpiece.”[^47] - **Test Procedures for Automatable Polywrap Film**, also called USPS-T-3204: “This specification covers the procedures required to test polywrap film used to enclose flat mail pieces for U.S. Postal Service automated sorting operations.”[^50] - **Polywrap and Polywrap Manufacturers**: “The Polywrap Manufacturers link is a downloadable document which lists polywrap manufacturers and distributors of polywrap approved for use on automation rate flat-size mailpieces in compliance with DMM standards effective February 1, 2007.”[^29] ## Checking a design [Mailpiece Design Analysts](https://postalref.com/guides/getting-help.md) are USPS employees trained to answer questions about mailpiece design.[^30] They give advice and issue rulings on whether a piece qualifies for automated rates.[^30] They help the businesses that design and make mailpieces, such as envelope manufacturers and printers.[^30] The Mailpiece Size Checker, at the top right of the [EDDM Online Tool](https://postalref.com/guides/saturation-mail.md), checks a piece against the USPS Marketing Mail flats size requirements.[^51] Mailers may check a TED-C letter with the TED-C Letters Template.[^17] A [national customer ruling](https://postalref.com/guides/mail-classes.md#classification) is a USPS decision on a proposed mailing's design and price eligibility, before it reaches a business mail entry unit.[^52] ## What goes wrong - A single-piece First-Class Mail letter with a nonmachinable trait pays the [nonmachinable surcharge](#machinability).[^7] - A [shortpaid](https://postalref.com/guides/paying-postage.md#postage-due) nonmachinable First-Class Mail letter goes back to the sender for more postage.[^14] - A mailing of TED-C pieces that miss the requirements pays [nonmachinable letter prices](https://postalref.com/products/alternative-designs.md#problems).[^53] - A TED-C piece that reaches the 5-inch minimum length only with its die-cut is nonmailable.[^18] - Polywrap film that fails any of the [film tests](https://postalref.com/products/polywrap-and-polywrap-manufacturers.md#problems) is unacceptable for USPS automated processing.[^50] - A letter envelope whose window intrudes into the barcode clear zone is not eligible for [NCOALink MPE](https://postalref.com/guides/move-update.md).[^54] - Improperly applied [package labels](https://postalref.com/guides/package-labels.md) can cause scanning problems and affect USPS tracking data.[^28] ## Index: 18 entries ### System (1) - [Mailpiece Size Checker](https://postalref.com/?q=Mailpiece%20Size%20Checker) ### Documents (3) - [Polywrap and Polywrap Manufacturers](https://postalref.com/products/polywrap-and-polywrap-manufacturers.md) - [TED-C Letters Template](https://postalref.com/guides/mailpiece-design.md#ted-c) - [Test Procedures for Automatable Polywrap Film](https://postalref.com/guides/mailpiece-design.md#polywrap) ### Terms (14) - [Alternative Designs](https://postalref.com/products/alternative-designs.md) - [aspect ratio](https://postalref.com/guides/mailpiece-design.md#machinability) - [barcode clear zone](https://postalref.com/guides/mailpiece-design.md#address-side) - [conventional trailing edge](https://postalref.com/guides/mailpiece-design.md#ted-c) - [DIE-CUT MEASUREMENT ZONES](https://postalref.com/guides/mailpiece-design.md#ted-c) - [flat-size mail](https://postalref.com/guides/mailpiece-design.md#shapes) - [letter-size mail](https://postalref.com/guides/mailpiece-design.md#shapes) - [Machinable Parcel](https://postalref.com/guides/mailpiece-design.md#shapes) - [mailing wrapper](https://postalref.com/guides/mailpiece-design.md#polywrap) - [nonmachinable](https://postalref.com/guides/mailpiece-design.md#machinability) - [Nonmachinable Stamped Letters](https://postalref.com/?q=Nonmachinable%20Stamped%20Letters) - [Nonstandard Parcel](https://postalref.com/guides/mailpiece-design.md#shapes) - [polywrap](https://postalref.com/guides/mailpiece-design.md#polywrap) - [TED-C letter](https://postalref.com/guides/mailpiece-design.md#ted-c) ## Sources [^1]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=130), PDF page 130: “One of five designations for mail (letter-size mail, flat-size mail, machinable parcel, irregular parcel, and outside parcel), based on physical dimensions (height, length, and thickness), physical characteristics, and weight.” [^2]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=118), PDF page 118: “A mail processing category that consists of letters and cards meeting minimum size standards and not exceeding the maximum letter-size mail dimensions of 11-1/2 inches long, 6-1/8 inches high, and 1/4 inch thick.” [^3]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=92), PDF page 92: “A mailpiece that exceeds one of the dimensions for letter-size mail (11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick) but that does not exceed the maximum dimension for the mail processing category (15 inches long, 12 inches high, 3/4 inch thick). … Flat-size mail must also be flexible. … Flat-size mail must be rectangular with four square corners or with finished corners that do not exceed a radius of 1/8 inch. … Flat-size mail may be unwrapped, sleeved, wrapped, or enveloped. … Minimum dimensions are different for flat-size mail claimed at automation prices. … A mailpiece that exceeds one of the dimensions for letter-size mail (11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick) but that does not exceed the maximum dimension for the mail processing category (15 inches long, 12 inches high, 3/4 inch thick). Flat-size mail must be rectangular with four square corners or with finished corners that do not exceed a radius of 1/8 inch. Flat-size mail must also be flexible. Minimum dimensions are different for flat-size mail claimed at automation prices. Flat-size mail may be unwrapped, sleeved, wrapped, or enveloped.” [^4]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=150), page 146: “The incapacity of a mailpiece to be sorted on mail processing equipment because of size, shape, content, or address legibility. … Such mail must be processed manually and may be subject to a surcharge or higher price. … The incapacity of a mailpiece to be sorted on mail processing equipment because of size, shape, content, or address legibility. Such mail must be processed manually and may be subject to a surcharge or higher price.” [^5]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=139), page 135: “For mailability, all mailpieces must be at least 0.007 inch thick. … For mailpieces 0.007 inch to 1/4 inch thick, the pieces must be at least 3-1/2 inches high and at least 5 inches long, except keys and identification devices. … The smallest dimensions permitted for all mailable matter or for a specific mail processing category or specific price. For mailability, all mailpieces must be at least 0.007 inch thick. For mailpieces 0.007 inch to 1/4 inch thick, the pieces must be at least 3-1/2 inches high and at least 5 inches long, except keys and identification devices.” [^6]: [DMM 101: Retail Mail, Physical Standards for Letters, Cards, Flats, and Parcels](https://pe.usps.com/text/dmm300/101.htm): “For pieces more than 6 inches long or 4-1/4 inches high, the minimum thickness is 0.009. … Pieces not meeting the 0.009 thickness are subject to a nonmachinable surcharge under … Has an aspect ratio (length divided by height) of less than 1.3 or more than 2.5. … Not more than 3.5 ounces (First-Class Mail letter-size pieces over 3.5 ounces pay flat-size prices). … A letter-size piece is nonmachinable if it has one or more of the following characteristics … Is polybagged, polywrapped, enclosed in any plastic material, or has an exterior surface made of a material that is not paper. … Has clasps, strings, buttons, or similar closure devices. … Contains items such as pens, pencils, keys, or coins that cause the thickness of the mailpiece to be uneven; or loose keys or coins or similar objects not affixed to the contents within the mailpiece. … Is too rigid (does not bend easily when subjected to a transport belt tension of 40 pounds around an 11-inch diameter turn). … Is less than 0.009 inches thick if the mailpiece is more than 6 inches long or 4-1/4 inches high. … Has a delivery address parallel to the shorter dimension of the mailpiece. … Is a self-mailer that is not prepared according to … Is a booklet that is not prepared according to” [^7]: [DMM 133: Retail First-Class Mail and USPS Ground Advantage Retail, Prices and Eligibility](https://pe.usps.com/text/dmm300/133.htm): “First-Class Mail Single-Piece and USPS Ground Advantage … The nonmachinable surcharge is charged per piece and applies to letter-size pieces that meet one or more of the nonmachinable characteristics in … Pieces mailed at the card price are not subject to the nonmachinable surcharge. … There are separate prices for stamped letters and for letters with metered postage affixed (Metered Mail price).” [^8]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=25), page 21: “Mail that can be scanned and processed by automated mail processing equipment such as a barcode sorter.” [^9]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=22), PDF page 22: “The dimension of a mailpiece expressed as a ratio of length (the direction parallel to the address) divided by height. … An aspect ratio between 1.3 and 2.5, inclusive, is required for automation compatibility. … For First-Class Mail letters, aspect ratio determines whether a nonmachinable surcharge applies. … For example, a postcard 5-1/2 inches long by 3-1/2 inches high has an aspect ratio of 1.57. … The dimension of a mailpiece expressed as a ratio of length (the direction parallel to the address) divided by height. For example, a postcard 5-1/2 inches long by 3-1/2 inches high has an aspect ratio of 1.57. An aspect ratio between 1.3 and 2.5, inclusive, is required for automation compatibility. For First-Class Mail letters, aspect ratio determines whether a nonmachinable surcharge applies.” [^10]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=89), page 85: “First-Class Mail comprises six products: (a) single-piece letters/postcards, (b) presorted letters/ postcards (nonmachinable, machinable, and automation prices), (c) flats (single-piece, presorted, and automation prices), (d) parcels (retail, Commercial Base, and Commercial Plus prices), (e) outbound single-piece First-Class Mail International, and (f) inbound single-piece First-Class Mail International.” [^11]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=161), page 157: “(1) Mail that does not meet the mail processing category of letter-size mail or flat-size mail.” [^12]: [Notice 123: Price List (effective October 4, 2026)](https://pe.usps.com/text/dmm300/Notice123.htm): “Large envelope-sized pieces that are rigid, nonrectangular, or not uniformly thick pay parcel prices. … Notice 123 • Effective October 04, 2026 … Letters that meet one or more of the nonmachinable characteristics in DMM 101.1.2 are subject to the $0.49 nonmachinable surcharge. … 1 | $0.82 | 2 | 1.11 … 1 | $1.69 | 2 | 1.98” [^13]: [Appendix C: ACS™ Product Code Information and Details](https://postalpro.usps.com/mnt/glusterfs/2024-12/AppendixC_ACSProductCodeInfoandDetails.pdf#page=6), page 5: “Letters including post cards - that do not exceed any of the dimensions for letter-size mail (i.e., 111/2 inches long, 6-1/8 inches high, 1/4 inch thick up to 3.5 ounces)” [^14]: [DMM 604: Postage Payment Methods and Refunds](https://pe.usps.com/text/dmm300/604.htm): “Shortpaid nonmachinable First-Class Mail letters are returned to the sender for additional postage. … Forever stamps are sold for the price of the current First-Class Mail single-piece 1-ounce letter price. … The following Forever stamps will always be equal in value to the applicable price for the price category printed on them, at the time of use: … The current FCM additional-ounce price … FCM non-machinable surcharge price” [^15]: [Full-Service Certification Standards](https://postalpro.usps.com/mnt/glusterfs/2024-05/FS%20Certification%20Standards%20and%20Application%20Form%20May%202024_0.pdf#page=57), page 57: “All First-Class Post cards must not exceed 4-1/4 inches in height and 6 inches in length and 0.016 inches in thickness” [^16]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=177), page 173: “A commercially produced and sold rectangular card designed for writing and mailing without an envelope and requiring First-Class Mail card or letter postage, depending on the dimensions. … A commercially produced and sold rectangular card designed for writing and mailing without an envelope and requiring First-Class Mail card or letter postage, depending on the dimensions. Postcards generally show a photograph or illustration on one side.” [^17]: [TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked Questions](https://postalpro.usps.com/mnt/glusterfs/2024-08/TED-C%20FAQ.v3.pdf#page=1), PDF page 1: “TED-C mailpieces are letter-size pieces that have a die-cut that extends past the conventional trailing edge of the mailpiece. … Only Full-Service First-Class Mail letters and USPS Marketing … Mail® letters with an address block Intelligent Mail® barcode (IMb) that meet the TED-C physical standards are eligible for automation prices. … No, as of February 1st, 2023, mailers are no longer required to obtain pre-approval from the Pricing & Classification Service Center (PCSC) to mail TED-C letters. … Mailers may use the TED-C Letters Template, available on PostalPro at: https://postalpro.usps.com/alternative_designs/ted_c_template, to determine if their mailpiece meets USPS requirements for TED-C mailability. … However, mailers are encouraged to submit requests for TED-C design reviews to a Mailpiece Design Analyst at MDA@usps.gov. … Note that the maximum length (10.5”) and maximum piece weight (2.5 oz.) for TED-C mailpieces are modified from regular automation letter standards.” [^18]: [Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter Prices](https://postalpro.usps.com/mnt/glusterfs/2024-06/TED%20C%20Requirements%20Final%20Updated.6.21.24.pdf#page=1), PDF page 1: “Die-cut must be only on the trailing (left) edge. … Domestic Mail Manual (DMM) 201.1.1c provides that machinable letter and postcard priced mailpieces must be, “Rectangular, with four square corners and parallel opposite sides”. … The conventional trailing edge is defined by a line drawn from the upper left corner to the lower left corner. … When measuring for minimum length and minimum aspect ratio, you cannot include the die-cut design. … When measuring for maximum length and maximum aspect ratio, the die-cut design must be included. (i.e., if the piece is 10 1/8” without the die-cut and the die-cut design makes the piece exceed the 10 ½” maximum, the piece is not eligible for automation letter prices and must be paid at the applicable nonmachinable letter price (See Price List – Notice 123)). … For example, if the piece is 4 ½” in length without the die-cut, and with the die-cut design allows the piece to meet the 5” minimum length, the piece is non-mailable” [^19]: [PostalPro: Alternative Designs](https://postalpro.usps.com/alternative_designs): “The USPS and the mailing industry have worked together to create requirements that will allow for the mailing of non-rectangular TED-C letter-size pieces at the automation letter prices. … Template with instructions for Trailing Edge Die-Cut (Ted-C) Letters.” [^20]: [DMM 201: Commercial Mail, Physical Standards](https://pe.usps.com/text/dmm300/201.htm): “USPS categorizes parcels into one of two mail-processing categories: machinable or nonstandard. … Dimensions: A parcel that measures more than 22 inches long, or 18 inches wide, or 15 inches high. … Weight: A USPS Marketing Mail parcel that weighs less than 3.5 ounces or any parcel that weighs more than 25 pounds. … A parcel is considered nonstandard if it has the following characteristics: … Cylindrical tubes or rolls. … A can, or wood or metal box. … Polywrap film, or similar coverings on flat-size mailpieces, except for pieces mailed at saturation, high-density plus, or high-density prices, must meet the standards in 4.5. … Only polywrap listed as approved on PostalPro at https://postalpro.usps.com may be used on flat-size mailpieces.” [^21]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=14), page 15: “Updated processing categories – retired processing category Irregular (4) and changed Nonmachinable (5) to Nonstandard” [^22]: [Postal Bulletin 22431: DMM Revision: Parcel Simplification (Dec 2015)](https://about.usps.com/postal-bulletin/2015/pb22431/html/updt_002.htm): “As a result, the Postal Service is taking the first step in this initiative by clarifying that the term “outside parcel” is a “nonmachinable parcel” in various sections of the DMM for consistency. … Although this revision will not be published in the DMM until January 17, 2016, these standards are effective immediately.” [^23]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=124), PDF page 124: “The physical capacity of a mailpiece to be sorted by mail processing equipment because its size, shape, configuration, and weight are within the specifications and tolerances of the equipment. … A mailpiece that is of the correct size, shape, and weight to be safely sorted by mail processing machinery such as a parcel sorting machine.” [^24]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=26), PDF page 26: “A price category for mail that is presorted and prebarcoded and that meets addressing, readability, and other requirements for mail that can be processed on automated equipment. … Automation prices are generally lower than prices for single-piece mail or nonautomation presorted mail.” [^25]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=153), page 149: “A rectangular area on the address side of the mailpiece that is 1/2 inch from the left and right edges of the mailpiece, 5/8 inch from the bottom edge, and 2-3/4 inches from the bottom edge. … A separate price category for Standard Mail pieces that either meet the size limits for flatsize mail or exceed the length and height for flatsize mail while not meeting the uniformity or flexibility requirements for flat-size mail.” [^26]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=27), page 23: “A rectangular area in the lower right part of a letter-size mailpiece that must be kept free of printing and symbols, except for the barcode itself. … This requirement allows automated processing machines to read or apply a barcode. … A rectangular area in the lower right part of a letter-size mailpiece that must be kept free of printing and symbols, except for the barcode itself. This requirement allows automated processing machines to read or apply a barcode.” [^27]: [Intelligent Mail® Barcode FAQ](https://postalpro.usps.com/mnt/glusterfs/2022-05/IMb_FAQ_5222v4.pdf#page=2), PDF page 2: “On letters, it can be placed either in the address block or in the barcode clear zone found on the lower right corner of the envelope. … On flats, the Intelligent Mail barcode can be placed anywhere on the address side as long as it is at least 1/8th inch from any edge of the piece.” [^28]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=48), page 48: “Always place the label fully on the address side of the package without overlapping the side or any other label. … When unmarked, the largest side of the box should be considered the address side. … Improperly applied shipping labels can cause scanning problems and affect the quality of tracking data provided by USPS.” [^29]: [PostalPro: Polywrap and Polywrap Manufacturers](https://postalpro.usps.com/operations/polywrap-and-polywrap-manufacturers-0): “The Polywrap Manufacturers link is a downloadable document which lists polywrap manufacturers and distributors of polywrap approved for use on automation rate flat-size mailpieces in compliance with DMM standards effective February 1, 2007. … Mailers may use polywrap in this list immediately, but are required to use approved polywrap from this list as of March 4, 2007 when using polywrap on automation rate flat-size First-Class Mail, Periodicals, and Standard Mail, and on barcoded Bound Printed Matter mailpieces.” [^30]: [Mailer's Technical Advisory Committee - Best Practices for ACS™](https://postalpro.usps.com/mnt/glusterfs/2022-05/ACS_BestPractices.pdf#page=44), page 44: “Postal employees specially trained to answer your questions regarding mail piece design. … These employees provide advice and issue rulings regarding acceptability for automated rates. … MDAs provide technical assistance on mail piece design to envelope manufacturers, printers, advertising agencies, and graphic designers.” [^31]: [Full-Service Certification Standards](https://postalpro.usps.com/mnt/glusterfs/2024-05/FS%20Certification%20Standards%20and%20Application%20Form%20May%202024_0.pdf#page=58), page 58: “The length of a flat is the longest dimension regardless of the address placement … The delivery address can be placed anywhere on the mailpiece at least 1/8 inch from any edge and it must be printed in the same read direction as the postage” [^32]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=36), PDF page 36: “A letter-size mailpiece of cardstock without an envelope, defined by its dimensions and physical construction. … A unique First-Class Mail price for such a mailpiece. … (1) A letter-size mailpiece of cardstock without an envelope, defined by its dimensions and physical construction. (2) A unique First-Class Mail price for such a mailpiece.” [^33]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=113), page 109: “A mail processing category for a nonmachinable parcel that does not meet the dimensions or minimum weight of a machinable parcel.” [^34]: [Publication 205 Electronic Verification System (eVS®) Business and Technical Guide](https://postalpro.usps.com/mnt/glusterfs/2024-07/eVS_pub205_July_2024_0.pdf#page=193), page 185: “Nonstandard fees and requirement for dimensional data disclosure applies to Priority Mail Express, Priority Mail, Parcel Select, and USPS Ground Advantage packages under the following conditions:” [^35]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=159), page 155: “A mail processing category for a mailpiece that exceeds the dimensions for machinable parcel or a high density item (other than a book or printed matter). … A parcel or mailpiece that, because of size, weight, shape, or contents, must be handled manually. … The mailpiece is called an outside because it cannot be placed into a sack or container. … A parcel or mailpiece that, because of size, weight, shape, or contents, must be handled manually. The mailpiece is called an outside because it cannot be placed into a sack or container.” [^36]: [DMM 233: Commercial First-Class Mail, Prices and Eligibility](https://pe.usps.com/text/dmm300/233.htm): “Commercial First-Class Mail Presorted cards and letters are charged as follows: … Nonautomation Nonmachinable: One price per presort level up to the maximum 3.5 ounces.” [^37]: [Postal Bulletin 22327: DMM revision, new standards for domestic mailing services, Not Flat-Machinables ended (Dec 2011)](https://about.usps.com/postal-bulletin/2011/pb22327/html/updt_001.htm): “We now end the NFM category as of January 2012.” [^38]: [Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guide](https://postalpro.usps.com/mnt/glusterfs/2024-02/IMpb_ACS_Technical_Guide.pdf#page=3), page 3: “On January 22, 2017, Standard Mail® underwent a name change and was rebranded as USPS Marketing Mail™” [^39]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=62), page 58: “On letter mail, the delivery address is usually placed in the lower right. … The location (destination) to which a mailpiece is delivered. Except for mail prepared with a detached address label, the piece must show the address of the addressee (intended recipient) on the side bearing postage stamps or postage indicia. On letter mail, the delivery address is usually placed in the lower right.” [^40]: [OneCode ACS® Technical Guide ](https://postalpro.usps.com/mnt/glusterfs/2019-10/OneCodeACSTechnicalGuide.pdf#page=10), page 10: “A domestic return address is required when ancillary services are requested. … First-Class Mail®, USPS Marketing Mail™ letters and flats, and Bound Printed Matter require the return address to be on the address side of the mailpiece in the upper left corner of the envelope or in the upper left corner of the addressing area.” [^41]: [Full-Service Certification Standards](https://postalpro.usps.com/mnt/glusterfs/2024-05/FS%20Certification%20Standards%20and%20Application%20Form%20May%202024_0.pdf#page=60), page 60: “Horizontally, the leftmost bar must be between 3-1/2 inches and 4-1/4 inches from the right edge of the piece … Vertically, the barcode must be within the area between 3/16 inch and 1/2 inch, both measured from the bottom edge of the piece” [^42]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=238), page 234: “An envelope with one or two openings (cutouts) on the address side through which a delivery address or barcode printed on the letter or insert placed in the envelope can be read. … An envelope with one or two openings (cutouts) on the address side through which a delivery address or barcode printed on the letter or insert placed in the envelope can be read. The openings must be covered with transparent material (such as glassine) for certain types of mail (such as Registered Mail).” [^43]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=11), page 7: “The area on a mailpiece containing the address to which USPS is to deliver a mailpiece.” [^44]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=196), PDF page 196: “A mailpiece element that is usually placed in the upper left corner of the mailpiece or address label to display the sender’s address. This address indicates where the sender wants the mail returned if it is undeliverable and where the sender will pay any fee due for that mail.” [^45]: [TED-C (Trailing Edge Die-Cut) Letters - Frequently Asked Questions](https://postalpro.usps.com/mnt/glusterfs/2024-08/TED-C%20FAQ.v3.pdf#page=2), PDF page 2: “The die-cut cannot extend more than 5/8” from the conventional trailing (left) edge. … The four zones represent the sensors on the machines, or where the lights are placed. … 1. Place the lower-left corner of the mailpiece on the template and align the bottom edge with the line. … 2. Place the upper-left corner of the mailpiece and align the top edge with the line. … Ensure that some part of the die-cut extension extends into Zones B or C. … Yes, the die-cut may be visible in emails provided to Informed Delivery® recipients. … However, to ensure die-cut visibility, the leftmost edge of the die-cut extension must be in Zone C of the TED-C Letter Template. … If the die-cut extension's leftmost edge is not in ZONE C, it may be acceptable to mail, but there may not be any visibility of the die-cut in Informed Delivery® for recipients.” [^46]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=169), page 165: “(1) Clear polythene film used to enclose mailpieces including automation flat-size pieces. … (1) Clear polythene film used to enclose mailpieces including automation flat-size pieces. (2) To enclose mailpieces with an automated process in which polythene is fed from reels under and around the pieces. The two edges are brought together and heat-sealed, and the top and bottom edges are crop-sealed to create the container.” [^47]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=129), page 125: “An envelope, sleeve, partial wrapper, or polywrap used to enclose a mailpiece.” [^48]: [Test Procedures for Automatable Polywrap Film](https://postalpro.usps.com/mnt/glusterfs/2018-02/USPS-T-3204DMMMappingTestProceduresforAutomatablePolywrapFilm.pdf#page=18), page 12: “Polywrap manufacturers must submit a polywrap formulation to approved laboratories for testing. … The Postal Service will include approved polywrap formulations in the List of Approved Polywrap.” [^49]: [Test Procedures for Automatable Polywrap Film](https://postalpro.usps.com/mnt/glusterfs/2018-02/USPS-T-3204DMMMappingTestProceduresforAutomatablePolywrapFilm.pdf#page=2), PDF page 2: “Requirements identified in the DMM 4.5.1 Polywrap Specifications refer to specific sections for test methods in USPS-T-3204 – Test Procedures for Automatable Polywrap Film.” [^50]: [Test Procedures for Automatable Polywrap Film](https://postalpro.usps.com/mnt/glusterfs/2018-02/USPS-T-3204DMMMappingTestProceduresforAutomatablePolywrapFilm.pdf#page=7), page 1: “This specification covers the procedures required to test polywrap film used to enclose flat mail pieces for U.S. Postal Service automated sorting operations. … Materials that do not meet all of the requirements here are unacceptable for Postal Service automated processing.” [^51]: [How to Create an EDDM Bulk Mailing](https://postalpro.usps.com/mnt/glusterfs/2019-05/How%20to%20Create%20an%20EDDM%20Bulk%20Mailing_052819.pdf#page=2), PDF page 2: “Use the Mailpiece Size Checker, located at the top right of the EDDM Online Tool, to make sure your mailpiece meets the USPS Marketing Mail® Flats size requirements.” [^52]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=144), PDF page 144: “A voluntary customer program administered by USPS that renders decisions on mailpiece design and price eligibility and issues a classification decision on the pieces in the mailer’s proposed mailing before it is presented at a business mail entry unit.” [^53]: [Trailing Edge Die-Cut (TED-C) Process for Eligibility at Automation Letter Prices](https://postalpro.usps.com/mnt/glusterfs/2024-06/TED%20C%20Requirements%20Final%20Updated.6.21.24.pdf#page=3), PDF page 3: “Pieces not meeting the TED-C requirements that are presented as a mailing will be charged nonmachinable letter prices.” [^54]: [Guide to Move Update](https://postalpro.usps.com/mnt/glusterfs/2024-01/Guide%20to%20Move%20Update.pdf#page=57), page 54: “A letter envelope containing a window that intrudes into the barcode clear zone is not eligible for MPE.” --- Unofficial. Not affiliated with or endorsed by the United States Postal Service. This is https://postalref.com/guides/mailpiece-design as Markdown.