Mailing Q&A

How can I design my mailing piece to ensure that it qualifies for the service class I need?

The best way is to refer to our "Mail Layout Guides." They show where clear space (free of any design elements) is needed to facilitate barcoding, addressing and permit imprinting so that the mail piece is eligible for your preferred mail service class.

What is CASS and NCOA used for?

USPS Link:

If the recipient has moved and left no forwarding address or the address is incorrect or missing an address element, the mailpiece could become undeliverable-as-addressed (UAA) mail.

Coding Accuracy Support System (CASS) standardizes your list to match Postal Service formats and then matches the address to as national database of valid addresses to ensure that the address is actually deliverable.

The National Change of Address (NCOA) system uses the USPS database to check for people and businesses that have filed a change of address with the USPS within the last 48 months. Performing this update satisfies the Move Update requirement for First Class and Standard mail. It also saves you money on printing and postage by updating a list. Studies have shown that this service can save users a significant cost of their mailings (in many cases up to 15% or more) and helps increase response rates.

Any address that cannot be standardized by CASS is invalid and cannot be mailed. Any NCOA changes must be updated to be mailed or they will be deleted. For more information go to the UPSP Move Update Link:

Is there a fee for a NCOA?

NCOA is used for virtually all mailings we do. The cost for processing your list through NCOA is included in the mail preparations charges

What happens to invalid addresses from my list (CASS/NCOA)?

Addresses that are identified by CASS as Undeliverable As Addressed are removed from the list and are returned to you in a separate file for correction. UAA addresses can only be mailed as nondiscounted First Class Mail. This is only done on your request. Addresses that cannot be updated by NCOA cannot be mailed either.

Can you remove duplicate addresses?

Yes, but only upon your request. Be sure to specify that you want this service.

Can you send a clean list back to me?

We would be happy to email the "cleaned up" version of your list to you, or send you the list of the questionable addresses we removed at your request. Just call us at 661-327-3228 to let us know what file format you would like to receive.

Can you use my mail permit?

We are able to mail from our service location using our mail permit. Mailing permits are tied to local USPS offices and may only be used in the locality where they are issued. If you'd like us to address your material and ship it to you, you could use your own permit and mail it from your location.

How and When should I send my mailing list?

It is important to remember that without your list, we cannot begin the mailing portion of your job. Therefore, you should send it to us at the same time as your printing order if at all possible. If you do not need your cards to mail immediately after the printing, you should make sure we have the list no later than 4 business days before your preferred mailing date.
There are several ways to submit your mailing list. If you are shipping your order to us, you can include your list on a diskette or CD. If you are ordering online through our Online Ordering System, you will be able to upload your mailing list along with your print materials. Please be sure to "zip" your list files before submitting them electronically. In all cases, clearly identify each submission with your Job #, your name, company and phone number. Also, please indicate the quantity and the file types, and provide any special instructions for processing the lists. A field layout is always appreciated and will help expedite processing your list.

What mailing list format should I send you?

The best file formats to send us for your mailing list are either Microsoft Excel or a tab or comma delimited text file.

Please give us a call at 661-327-3228 if you're not sure what format you have or if we can use it. We can walk you through getting your address list into a viable file format and uploaded to us. The most common file formats and extensions for mailing lists are:

  • .CSV Comma Delimited
  • .ASC ASCII text file
  • .TXT ASCII text file
  • .XLS Microsoft Excel Spreadsheet
  • .MDB Microsoft Access

Once you have your list prepared, you can upload it to us at For more mailing list information check out: Getting Your Mail List Ready..

What's the best way to break out the address fields or column names when exporting or preparing a mailing list?

The minimum required fields are: Name, Address1, City, State, Zip. Optional ones might be Business Name, Address2, Dept., etc. There is a limit of 5 lines for any address which in turn limits the number of different fields we can include.

Can you insert additional pieces into my envelope, flyer, etc.?

Yes we can do inserting. Please contact us to discuss your particular needs and to get an accurate price quote.

Do you offer tabbing (also called wafer sealing)?

Any mailing piece that requires tabbing is automatically tabbed according to postal regulations. If you need tabbing but you don't need us to mail your material for you, please call us for pricing.

Will coatings interfere with addressing and mailing?

We can address aqueous-coated pieces, but there will be an additional charge.
We cannot address anything that has a UV coating.

Can I have you mail some of my order and ship the rest?

We'll ship the quantity which is not mailed to the shipping address you provide on the order form.

How long will it take to get my piece into the mail?

Add one to two days production time for mailing..

Do you offer mailing services for items not printed with you?

Yes. Please call us to schedule your mailing.

Can you mail to Canada or other non-U.S. addresses?

We would be happy to mail to your foreign addresses. If you have a mail piece that folds, most countries require that it be sealed on all sides or placed in an envelope.

Do you accept my mailing list as Cheshire labels, tapes, tape cartridges or DAT tapes?

No. We do NOT accept Cheshire labels, tapes, tape cartridges or DAT tapes.

What fields must I include to make sure my mail is delivered?

For proper addressing, your list must include a recipient's name (or generic name such as "Current Resident"), street name and number (include apt #, PO Box, or suite #), city, state and zip code. Business lists should also include Company names and may optionally include Title & Department fields. Find out more information at Getting Your Mail List Ready..

Is there a minimum quantity you can mail?

Postal regulations require a minimum of 500 pieces to qualify for 1st Class Presort and 200 pieces for Presorted Standard (Bulk Rate). Any less than these amounts will be sent out at the single-piece 1st class rates. Remember the minimum quantity refers the remaining qualified records after all processing and deduping.

I have been gathering my list for several years and I know some people have moved. Is there some way to update it with new addresses?

Yes, read more in What’s Move Update All About.

I only have self-adhesive mailing labels. Can you use those to complete my mailing?

Yes, in those cases where you do not have an electronic version of your list, we can apply your labels instead of ink jet addressing. However, since we will not be able to apply postal barcodes to your mail, no presort discounts are available. Therefore, your cost for the mailing will be the full First Class postage, plus a Mailing Services fee and a per piece charge to hand-apply the labels. Contact us for details and a cost estimate.

What type of security and protection do you provide for the confidential information contained in my mailing list?

We will take reasonable steps to maintain the confidentiality, safekeeping and protection of confidential information contained in a Customer's mailing list. At all times it is Customer's or Customer's list vendor's responsibility to maintain a duplicate copy of their mailing list(s).

Mailing Services Glossary of Terms

Address - The location to which the USPS is to deliver or return a mailpiece. It consists of certain elements such as recipient name, street name and house number, and city, state, and ZIP Code as required by the mail class.

Address Change Service (ACS) - An automated process that provides change-of-address information to participating mailers who maintain computerized mailing lists. The information is captured in the Computerized Forwarding System (CFS) units and sent to mailers on electronic media, which reduces the volume of manual change-of-address notices.

Address Correction Service - A system of ancillary service endorsements that allows mailers to obtain the addressee's new (forwarding) address or the reason for nondelivery.

Addressee - The person or organization to whom a mailpiece is addressed as shown in the delivery address.

Address Element Correction (AEC) - A process that identifies and revises incomplete or incorrect computerized address files and then attaches ZIP+4 and carrier route codes. It involves computer matching address records that cannot be coded using CASS-certified address matching software.

Ancillary Service - Forwarding, return, or address correction service included within a mail class. Depending on the mail class, these services are performed at a charge or at no additional charge, if and when the service is actually rendered.

Ancillary Service Endorsement - A marking used by a mailer to request the new address of an addressee and to provide the USPS with instructions on how to handle mail that is undeliverable as addressed. i.e. Change Service Requested, Forwarding Service Requested, Return Service Requested and Address Service Requested. One of these endorsements may be required if NCOA is not used for the Move Update requirement. (Also see address correction service.)

Army Post Office (APO) - A branch of a designated USPS civilian post office, which falls under the jurisdiction of the postmaster of either New York City or San Francisco, that serves either Army or Air Force personnel. (Also see military post office.)

Aspect Ratio - The dimension of a mail piece 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 some First-Class Mail, aspect ratio is used to determine whether a nonstandard surcharge applies.

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

Automation Discount - A postage reduction offered to mailers who prebarcode their mail pieces and meet addressing, readability, and other requirements for processing on automated equipment.

Barcode (BC) - A series of vertical bars and spaces that represent any numerical series, most often a correct ZIP Code for the delivery address on a mail piece. The barcode facilitates automated processing by barcode readers and scanners. These codes make it possible for the mail processing equipment to quickly process these pieces, lowering mail-processing and delivery costs. The savings are passed on to consumers through lower postage rates. (Also see delivery point barcode and Postal Numeric Encoding Technique.)

Barcode Clear Zone - A rectangular area in the lower right part of a letter-size mail piece 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.

Barcode Read Area - A small area within the barcode clear zone in which the barcode must be printed. This area is defined by the position of the leftmost bar of the barcode and the bottom edge of the bar.

Bulk Mail - Mail that is rated for postage partly by weight and partly by the number of pieces in the mailing. The term is generally used to refer to Standard Mail (A).

Bulk Mail Center (BMC) - A highly mechanized mail processing plant that distributes Standard Mail in piece and bulk form.

Bulk Rate - The postage rate for mail pieces that are part of a large-volume mailing and that meet minimum volume and preparation requirements. The term is most often applied to Standard Mail (A) mailings, which usually consist of a per piece rate plus a per pound rate.

Business Mail Entry Unit (BMEU) - The area of a postal facility where mailers present bulk, presorted, and permit mail for acceptance. The BMEU includes dedicated platform space, office space, and a staging area on the workroom floor.

Business Reply Mail (BRM) - A domestic service that allows a mailer to receive First-Class Mail back from customers and pay postage only for the pieces returned to the mailer from the original distribution of BRM pieces. These pieces must have a specific address and format. Postage and fees are collected when the mail is delivered back to the original mailer

Cancel - To render a postage stamp (except a precanceled stamp) unusable, usually at the point of original entry into the mailstream. This is done by using a facer-canceler or a handstamp Cancellation - A postmark that contains the post office name, state, ZIP Code, and month, day, and year that the mail matter was canceled

Carrier Route (CR) - The addresses to which a carrier delivers mail. In common usage, carrier route includes city routes, rural routes, highway contract routes, post office box sections, and general delivery units.

Carrier Route File - The official listing of all city and non-city delivery post offices, available to mailers in a standardized format. It contains schemes for city routes, rural routes, highway contract routes, post office box sections, and general delivery units. The data are formatted by ZIP Code, street name, and ranged street numbers.

Carrier Route Information System (CRIS) - The official city delivery scheme that lists all city and non-city delivery post offices, which is available to mailers in a standardized format. It contains schemes for city routes, rural routes, highway contract routes, post office box sections, and general delivery units. The data are formatted by ZIP Code, street name, and street number range. Delivery statistics (possible deliveries) for each carrier route are also included in the file. (Also see Coding Accuracy Support System.)

Carrier Route Presort Mail - Mail sorted by carrier route to qualify for discount postage rates. The mail requires no primary or secondary distribution. The term is a general descriptor of the available rates for this type of preparation, which includes Enhanced Carrier Route Standard Mail, automation carrier route First-Class Mail, carrier route Periodicals, and carrier route Bound Printed Matter. Unless mailed at automation rates, carrier route mail pieces usually do not bear a barcode. (Also called Enhanced Carrier Route Standard Mail.) Version 1.1 123 5/19/09

Certified Mail - A service that provides the sender with a mailing receipt. A record of delivery is kept at the post office of address. This type of mail must be sent at First-Class Mail or Priority Mail rates. Certified mail may be combined with return receipt service and restricted delivery service.

Change-Of-Address (COA) - A customer move from one mailing address to another.

Change-Of-Address Order - A customer's notification to the post office of a permanent or temporary change of address (COA) by using Form 3575, Change of Address Order, or other written or personal notice

Clear Space Area in lower right of a mailing piece where the address and barcode is printed. This area must be blank or with less than 10% ink density, to ensure machine readability and therefore be eligible for your desired mail service class. Refer to our "U.S. Mail Layout Guides" for more information and help in preparing your layout. (See also Barcode Clear Zone)

Coding Accuracy Support System (CASS) - A service offered to mailers, service bureaus, and software vendors 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 provides a common platform to measure the quality of address matching software and to diagnose and correct software problems.

CASS Certification - Coding Accuracy Support System (CASS) improves delivery of your mail piece and maximizes postage savings by adding Zip+4 codes to your mailing list where possible. The CASS Certification process also helps determine certain address problems and standardizes addresses to Postal Service formatting. The correct Zip+4 allows us to apply postal barcodes to your mail pieces, qualifying your mail for Mail Class discounts.

Coil - A roll of postage stamps (usually in quantities of 100, 500, 3,000, or 10,000

Courtesy Reply Mail (CRM) - Envelopes or postcards that a mailer provides to its customers to expedite delivery of their responses. The customer affixes the reply postage before mailing.

Dead Mail - Mail that is undeliverable as addressed and cannot be returned to the sender (usually because there is no return address on the piece).

Delivery Address - The location (destination) to which the USPS is to deliver a mail piece. Except for mail prepared with a detached address label, the piece must show the address of the addressee (intended recipient) on the side bearing the postage. It is usually placed in the lower right. (Compare with return address.)

Delivery Address Format - Address elements required by the USPS on all mai lpieces - that is, the intended recipient's name; either general delivery, a house or building number and street name (plus apartment/suite number, if applicable), or a post office box number or rural route or highway contract route designation with a box number; and city, state or state abbreviation, and ZIP Code or ZIP+4. Placement of this information on the mailpiece determines the dimension considered the length of letter size mail. (Compare with alternative addressing format.)

Delivery Point Barcode (DPBC) - A POSTNET barcode that consists of 62 bars with beginning and ending frame bars and 5 bars each for the nine digits of the ZIP+4 code, the last 2 digits of the primary street address number (or post office box, etc.), and a correction digit. The DPBC allows automated sortation of letter mail to the carrier level in walk sequence.

Delivery Point Code - In mail processing, the finest depth of code to which a mail piece can be sorted by its address. It is usually the 11-digit numeric code formed from the ZIP+4 and represented by the Version 1.1 124 5/19/09 delivery point barcode (DPBC).

Destination Bulk Mail Center (DBMC) rate - A rate available for Standard Mail (A) and Standard Mail (B) Parcel Post that is properly prepared and entered by the mailer at the BMC or other designated postal facility that serves the delivery address on the mail.

Destination Delivery Unit (DDU) rate- A rate available for Periodicals and Standard Mail that is properly prepared and entered by the mailer at the delivery unit that serves the delivery address on the mail.

Destination Sectional Center Facility (DSCF) rate- A rate available for Periodicals (except In-County) and Standard Mail that is properly prepared and entered by the mailer at the sectional center facility (SCF) (or, for certain Parcel Post, at the BMC) that serves the delivery address on the mail.

Detached Address Label (DAL) - Paper or cardboard stock used to carry address information when preparing a mailing of unaddressed Periodicals flats, Standard Mail (A) flats or merchandise samples, or unaddressed Bound Printed Matter.

Direct Mail - Another name for advertising mail sent to targeted markets. It can be any mail class, but it is usually Standard Mail (A).

Exceptional Address - An alternative addressing format that indicates that the mail piece should be delivered to the current resident if the addressee has moved. i.e. “or Current Resident”. (Compare with occupant address and simplified address.)

Flat-size Mail - A mail piece 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). Dimensions are different for automation rate flat-size mail eligibility. Flat-size mail may be unwrapped, sleeved, wrapped, or enveloped

Forward - To redirect mail to the intended recipient's new delivery address in cases where Form 3575, Change of Address Order, or other written or personal notice has been filed with the local post office. (Also see Address Change Service, address correction service, and ancillary service.)

Highway Contract Route (HCR) - A route of travel served by a postal contractor to carry mail over highways between designated points. Some HCRs include mail delivery to addresses along the line of travel. Formerly called star route.

Ink Jet Addressing We use state of the art, high-speed, ink jet technology for accurate addressing and bar coding that meets or exceeds USPS addressing regulations. Ink Jet addressing prints directly on the mailpiece, allowing for additional variable print fields to be used for marketing or transactional information.

Letter-size Mail - A mail processing category of mail pieces, including cards, that do not exceed any of the dimensions for letter-size mail (that is, 11-1/2 inches long, 6-1/8 inches high, 1/4 inch thick

Machinable - The capacity of a mail piece to be sorted by mail processing equipment. (Compare with non-machinable.)

Mailbox - Any private receptacle or container used by customers to receive mail either at their residence or at the curbside

Mailer - An entity that prepares and/or presents a mailing to the USPS. In some cases, a mailer is the agent for the actual owner of the mail. Version 1.1 125 5/19/09

Mail Fraud - A scheme to get money or other assets from a postal customer by offering a product, service, or investment opportunity that does not live up to its claims. Prosecutors must prove that the claims were intentionally misrepresented and that the mails were used to carry out the scheme. (Also see fraud order.)

Mailing Agent - A private third party that engages in a principal-agent relationship to mail bulk mail.

Mailing List - A group of names and addresses to which mail pieces in the corresponding mailing are addressed

Metered Mail - Any mail class (except Periodicals) with postage printed by a USPS-approved postage meter.

NCOA (National Change of Address) - Over 40 million Americans change their address every year. The National Change of Address (NCOA) system uses the USPS database to check for people and businesses that have filed a change of address with the USPS within the last 48 months. Performing this update on a list saves you money on printing and postage by updating a list. Studies have shown that this service can save users a significant cost of their mailings (in many cases up to 15% or more) plus help increase response rates. We compare your list with the address change orders given to the Post Office. Your list is automatically updated with that person or business' new address. We provide you with this a list of the names with changes and their new address (some change to valid addresses, others change to non-updateable addresses). Due to postal regulations and USPS privacy rules, a NCOA Processing Acknowledgement Form must be filled out and kept in our files before we can create you account and process your list through NCOA.

Nonmachinable - The incapacity 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.

Nonprofit Rate - A preferred rate for a Periodicals publisher authorized as a nonprofit organization.

Nonprofit Standard Mail - A subclass of Standard Mail that is available only to qualified organizations specified by U.S. statute.

Nonreadable Mail - Mail whose address cannot be deciphered by an optical character reader.

Occupant Address - An alternative addressing format that uses on one of four designations (that is, postal customer, occupant, householder, or resident) rather than an addressee name at a specific street address or post office box number, or rural route and box number; and post office, state, and ZIP Code. (Compare with exceptional address and simplified address.)

OCR Read aArea - A rectangular area on the address side of the mail piece that is 1/2 inch from the left and right edges of the mail piece, 5/8 inch from the bottom edge, and 2-3/4 inches from the bottom edge. (Also see optical character reader.)

Optical Character Reader (OCR) - An automated mail sorting machine that interprets the address information on a letter-size mail piece and sprays the corresponding ZIP Code information onto the piece as a barcode. The OCR consists of a mail feed unit, transport unit, stacker modules, computer with a control system, video monitor, and printer.

Optional Endorsement Line (OEL) - A series of specific printed characters on the top line of the address block that identifies the sortation level of a package or bundle and may contain an ACS participant code. The OEL is used in place of package labels. Version 1.1 126 5/19/09

Periodical Publication - Printed matter (a magazine, newspaper, or other publication) that is issued on a regular, stated basis.

Periodicals - A class of mail consisting of magazines, newspapers, or other publications formed of printed sheets that are issued at least four times a year at regular, specified intervals (frequency) from a known office of publication. Periodicals usually must have a legitimate list of subscribers and requesters

Postage Meter - A mechanical or electromechanical device that can print one or more denominations of an authorized postage indicia. It is available for lease only from designated manufacturers. (Also see metered mail.)

Postage Stamp - A gummed or self-adhesive paper stamp affixed to mail as payment for postal services. Types of stamps include definitive stamp (regular-issue stamp), special-issue stamp, and commemorative stamp. (Compare with metered postage.)

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

Postal Numeric Encoding Technique (POSTNET) - The barcode system used on letter-size and flat size mail pieces for encoding the delivery point information and ZIP+4 code information. (Also see delivery point barcode.)

Postal Rate Commission (PRC) - An independent federal agency that makes recommendations on USPS requests for changes in postal rates and mail classifications. The five commissioners are nominated by the President and approved by the U.S. Senate

Precancel - To cancel postage stamps or stamped envelopes before mailing. The USPS sells precanceled postage to mailers of Presorted (including automation rate) First-Class Mail and Standard Mail (A). If authorized, bulk mailers may precancel their own postage.

Precanceled Stamp - A postage stamp canceled by marking across the face before it is sold to mailers for use with bulk mailings. Also, a stamp designated by the USPS as a precanceled stamp without cancellation marks. Mailpieces with these stamps do not go through a canceling machine at the time of mail processing. Precanceled postage is an optional postage payment method for mailings at Presorted and automation First-Class Mail rates and at all Presorted Standard Mail (A) rates. (Also see precancel.)

Presort - The process by which a mailer prepares mail so that it is sorted to the finest extent required by the standards for the rate claimed. Generally, presort is performed sequentially, from the lowest (finest) level to the highest level, to those destinations specified by standard and is completed at each level before the next level is prepared. Not all presort levels are applicable to all mailings.

Presort Accuracy Validation and Evaluation (PAVE) - A voluntary program in which the USPS tests vendors' presort software and hardware products to determine their accuracy in sorting address information according to USPS standards and producing standardized supporting documentation

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 Standard - The postage rate for Standard Mail (A) pieces that are part of a mailing and that meet minimum volume and preparation requirements

Residual Mail - Matter remaining after completion of a presort sequence. It lacks the volume set by standard to require or permit package, tray, or sack preparation to a particular destination. Residual mail usually does not qualify for the presort rate. (Also called non-qualifying mail and working mail.)

Return Address - A mailpiece element that is usually placed in the upper left corner of the mail piece to indicate the address of the sender. 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. (Also see undeliverable as addressed.)

Return Receipt - The mailing card (Form 3811 for domestic and Form 2865 for international) signed by the addressee of an article and mailed back to the sender as evidence of delivery. This supplemental mail service is available for a fee when using Express Mail or recorded delivery, certified mail, collect on delivery, mail insured for more than $50, registered mail, or return receipt for merchandise.

Sectional Center Facility (SCF) - A postal facility that serves as the processing and distribution center (P&DC) 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

Simplified Address - An alternative addressing format used when delivery of identical mail is requested to every customer on a rural route or highway contract route, or to all post office box customers at a post office without city carrier service. Instead of listing the name and address of the addressee, the mailer may use "postal customer." It may also be used by government agencies for official mail sent to all stops on city routes and post office boxes at post offices with city delivery service. In such cases, these formats may be used: "Postal Customer," "Residential Customer," and "Business Customer," depending on the type of coverage requested. (Compare with exceptional address and occupant address.)

Standard Mail (A) - Standard Mail matter that weighs less than 16 ounces. It comprises the subclasses of Regular Standard Mail, Nonprofit Standard Mail, Enhanced Carrier Route Standard Mail, and Nonprofit Enhanced Carrier Route Standard Mail. These subclasses include circulars, printed matter, pamphlets, catalogs, newsletters, direct mail, and merchandise. Standard Mail (A) may be sent at presorted rates and at automation rates.

Standard Mail (B) - Standard Mail matter that weighs 16 ounces or more but not more than 70 pounds. It comprises four subclasses: Bound Printed Matter, Library Mail, Parcel Post, and Special Standard Mail.

Undeliverable As Addressed (UAA) - Mail that the USPS cannot deliver as addressed and must forward to the addressee, return to the sender, or send to a mail recovery center. (Also see address correction service, Computerized Forwarding System II, markup, nixie, return address, throwback case, and tracer.)

ZIP (Zone Improvement Plan) Code - Established in 1963, the system of 5-digit codes that identifies the individual post office or metropolitan area delivery station associated with an address. The first three digits identify the delivery area of a sectional center facility or a major-city post office serving the delivery address area. The next two (the fourth and fifth) digits identify the delivery area of an associate post office, post office branch, or post office station. All post offices are assigned at least one unique 5-digit code. ZIP+4 is an enhanced code consisting of the 5-digit ZIP Code and four additional digits that identify a specific range of delivery addresses. ZIP Code is a USPS trademark. (Also see two-pass.)

ZIP+4 - The nine-digit numeric code, established in 1981, composed of two parts: (a) The initial code: the first five digits that identify the sectional center facility and delivery area associated with the address, followed by a hyphen; and (b) the four-digit expanded code: the first two additional digits designate the sector (a geographic area) and the last two digits designate the segment (a building, floor, etc.). ZIP+4 is a USPS trademark. ZIP+4 barcode - A nine-digit POSTNET barcode consisting of 52 vertical bars