New to direct mail or just need a quick reference? This glossary covers the most important terms in direct mail, printing, and postal services — from CASS certification to ZIP+4 codes. Use the alphabet navigation to jump to any letter.
A
Address Standardization
The process of formatting a mailing address to conform to USPS standards, including correct abbreviations, ZIP+4 codes, and delivery point codes. Required for automation discounts.
Automation Mail
Mail that qualifies for USPS discounts by meeting strict address accuracy, barcode, and sortation requirements. Automation rates are significantly lower than non-automation rates.
ACS (Address Change Service)
A USPS service that provides electronic notification of address changes, undeliverable addresses, and other address corrections for mail pieces bearing an IMb barcode.
B
Bulk Mail
A general term for large-volume mailings that qualify for discounted USPS postage rates. Requires a minimum of 200 pieces or 50 lbs and a USPS permit. Also called Marketing Mail or Standard Mail.
Bulk Mail Center (BMC)
A large USPS processing and distribution facility that handles bulk mailings. Now called Sectional Center Facilities (SCFs) or Network Distribution Centers (NDCs).
C
CASS Certification
Coding Accuracy Support System — a USPS program that certifies address-matching software for accuracy. CASS-certified processing corrects addresses, assigns ZIP+4 codes, and is required for automation postage discounts.
Carrier Route
A specific geographic area assigned to a single USPS mail carrier. Each carrier route has a unique 4-character code appended to a ZIP code (e.g., 21801-C001). EDDM mailings target entire carrier routes.
Commingling
Combining presorted mail from multiple mailers into a single mailing to achieve deeper sortation levels (3-digit, 5-digit, carrier route) and lower postage rates than any single mailer could qualify for alone.
Co-Palletization
A USPS-approved process where mail from multiple mailers is combined on pallets to qualify for destination entry discounts, reducing postage costs for all participating mailers.
D
Data Hygiene
The process of cleaning and updating a mailing list to remove duplicates, correct addresses, update moved records via NCOA, and suppress undeliverable or opted-out addresses. Reduces wasted postage and improves deliverability.
Delivery Point Barcode (DPBC)
A USPS barcode that encodes the full delivery address including ZIP+4 and delivery point, enabling automated sorting to the individual mailbox level.
Delivery Point Validation (DPV)
A USPS process that verifies an address is a real, deliverable location in the USPS database. DPV-confirmed addresses qualify for automation discounts and reduce undeliverable mail.
Demographics
Statistical characteristics of a population segment used to target mailing lists, including age, income, household size, homeownership, marital status, and purchasing behavior.
Drop Shipping
Transporting presorted mail directly to a USPS Sectional Center Facility (SCF) or destination delivery unit (DDU), bypassing origin processing. Earns significant postage discounts (up to $0.05–$0.08 per piece).
E
EDDM (Every Door Direct Mail)
A USPS program that allows mailers to deliver to every address on selected carrier routes without a mailing list. Available in two versions: EDDM Retail (for small mailers at the post office) and EDDM BMEU (for larger volume through a mail house). Postage is approximately $0.203 per piece (2026).
eDoc (Electronic Documentation)
The electronic submission of mailing documentation to USPS via PostalOne! or the Mailer Scorecard system. Required for Full-Service mailings to claim automation discounts and access tracking data.
F
First-Class Mail
A USPS mail class for letters, postcards, and flats weighing up to 3.5 oz (letters) or 13 oz (flats). Includes forwarding and return service, 1–5 day delivery, and costs $0.593 per piece (2026 single-piece rate). Presorted First-Class starts at $0.443.
Flat
A large mail piece that is flexible, rectangular, and between 6.125" × 11.5" and 12" × 15". Flats include large envelopes, newsletters, and EDDM-compliant mailers. They have different postage rates than letter-size pieces.
Folder Inserter
A mailing machine that automatically folds documents and inserts them into envelopes. Quadient folder inserters can process hundreds to thousands of pieces per hour, dramatically reducing manual labor costs for statement and letter mailings.
Full-Service IMb
A USPS program requiring electronic documentation, unique barcodes on every mail piece and container, and use of Intelligent Mail barcodes. Provides postage discounts, free ACS, and access to Informed Delivery and Mailer Scorecard data.
G
Geocoding
The process of assigning geographic coordinates (latitude/longitude) to addresses. Used in direct mail to map delivery areas, analyze customer distribution, and select carrier routes for EDDM campaigns.
I
IMb (Intelligent Mail Barcode)
A 65-bar USPS barcode that encodes routing information, a unique piece identifier, and service type codes. Required for Full-Service mailings. Enables mail tracking, ACS notifications, and Informed Delivery.
IMPB (Intelligent Mail Package Barcode)
The package equivalent of the IMb, used on parcels and packages to enable tracking through the USPS network.
Informed Delivery
A free USPS consumer service that emails subscribers grayscale images of their incoming letter-size mail each morning. Mailers can add color ride-along images and clickable URLs to enhance their pieces at no extra cost.
Ink Jet Addressing
A high-speed printing method used to apply addresses, barcodes, and variable data directly onto mail pieces using inkjet technology. Faster and more cost-effective than laser printing for large volumes.
L
Lettershop
A facility that provides mail processing services including printing, folding, inserting, addressing, barcoding, presorting, and USPS entry. A full-service lettershop like Mail Movers handles every step from artwork to delivery.
List Broker
A company that compiles, manages, and sells mailing lists of consumers or businesses. Lists can be targeted by demographics, geography, purchase behavior, industry, and dozens of other criteria.
M
Marketing Mail
A USPS mail class (formerly Standard Mail or Bulk Mail) for advertising, promotional, and informational pieces weighing up to 16 oz. Postage starts at $0.178 per piece (2026 presorted rate). Does not include forwarding or return service by default.
Mailer Scorecard
A USPS tool that grades mailers on the quality of their Full-Service submissions, including barcode uniqueness, eDoc accuracy, and container label compliance. Poor scores can result in postage assessments.
Mail Piece Design
The process of creating a mail piece that meets USPS physical standards for size, weight, aspect ratio, barcode clear zones, and paper stock — while also being visually effective for the recipient.
MMScope
Mail Movers' proprietary omnichannel marketing platform that integrates direct mail with mail tracking, call tracking, social media audience matching, and online retargeting. Boosts campaign ROI by up to 46%.
N
NCOALink
National Change of Address Link — a USPS-licensed database of approximately 160 million permanent change-of-address records. Processing a list through NCOALink updates addresses for people who have moved in the past 48 months, reducing undeliverable mail.
Non-Profit Rate
A discounted USPS postage rate available to qualifying 501(c)(3) organizations. Non-profit Marketing Mail rates are approximately 40% lower than standard Marketing Mail rates.
P
Permit Imprint
A pre-printed indicia on a mail piece that replaces a stamp or meter impression. Requires a USPS permit and annual fee. Allows high-volume mailers to pay postage in bulk rather than affixing individual stamps.
Postage Meter
A machine that prints postage directly onto envelopes or tape strips, accounting for the postage used. Modern Quadient postage meters connect to USPS servers to download postage funds and print compliant indicia.
PostalOne!
The USPS web-based system used by mailers and mail service providers to submit electronic documentation (eDoc), pay postage, and access mailing reports. Required for Full-Service IMb mailings.
Presort
The process of sorting mail by destination ZIP code before submitting to USPS. Presorted mail earns postage discounts because it reduces USPS processing costs. Levels include 5-digit, 3-digit, SCF, and carrier route sorts.
Psychographics
Lifestyle, interest, and behavioral characteristics used to target mailing lists beyond basic demographics. Includes hobbies, political affiliation, purchase history, and values.
R
Response Rate
The percentage of mail recipients who respond to a direct mail campaign. Industry average response rates are 5.3% for house lists and 2.9% for prospect lists (DMA, 2024). Significantly higher than email (0.6%) and digital display ads.
Return on Investment (ROI)
The financial return generated by a direct mail campaign relative to its cost. Direct mail delivers a median ROI of 29% (ANA, 2023), higher than paid search (23%) and online display (16%).
S
Saturation Mailing
A mailing that targets every address (or every residential or business address) on selected carrier routes, achieving maximum market coverage. EDDM is the most common saturation mailing method.
SCF (Sectional Center Facility)
A USPS processing and distribution facility that serves a geographic area defined by a 3-digit ZIP code prefix. Drop-shipping mail to an SCF earns a postage discount of approximately $0.028–$0.044 per piece.
Seed Name
A known address added to a mailing list to verify delivery and timing. When the seed name receives the mail piece, the mailer knows the campaign has been delivered to that area.
Suppression File
A list of addresses, names, or phone numbers to be excluded from a mailing. Common suppression files include do-not-mail requests, existing customers, competitors, and deceased individuals.
T
Tabbing / Wafer Sealing
Applying small adhesive tabs or wafer seals to self-mailers and folded pieces to keep them closed during mail processing. USPS requires tabbing on certain self-mailer formats to prevent them from opening in automated equipment.
Targeted Mailing List
A curated list of prospects selected by specific criteria such as geography, demographics, income, homeownership, or business type. Targeted lists improve response rates by reaching only the most likely prospects.
U
USPS Full-Service Certification
A USPS designation for mailers and mail service providers who meet all requirements for Full-Service Intelligent Mail, including unique IMb barcodes, electronic documentation via PostalOne!, and container-level barcoding. Provides postage discounts, free ACS, and Mailer Scorecard access.
USPS Marketing Mail
See Marketing Mail. The official USPS name for the mail class formerly known as Standard Mail or Bulk Mail.
V
Variable Data Printing (VDP)
Digital printing technology that personalizes each mail piece with unique text, images, offers, or QR codes based on recipient data. VDP can increase response rates by 135% compared to static mail pieces (InfoTrends).
W
Wafer Seal
See Tabbing / Wafer Sealing.
Z
ZIP+4
A 9-digit ZIP code (e.g., 21801-3456) that identifies a specific block face, building, or delivery point. Required for automation discounts. Assigned by CASS-certified address processing software.