Getting a postcard returned at the post office counter is a gut-punch. You paid for design and printing and drove a stack of mail down there ready to go. Then you learn that one size or label requirement disqualifies the whole job. Every year, business owners run into preventable EDDM rejections, and the frustrating part is that the rules are not secret. They are published, specific, and learnable. Read these before you approve a print file.
Every Door Direct Mail, administered by the U.S. Postal Service, lets a business mail a printed piece to every address on a carrier route without buying or renting a mailing list. You pick routes and pay a flat per-piece postage rate. The carrier then delivers one piece to every deliverable address on those routes.
What it is not: first-class or addressed mail. Nor is it flexible about piece specifications. Because the mail is sorted and bundled by the post office in a specific way, every piece in the drop must conform to the same size, weight, and preparation rules. There is no wiggle room for "close enough."
If you want a broader picture of how the program works and what it costs before getting into the rules, the post What EDDM Actually Costs covers the per-piece postage rates and the other expenses that add up.
The USPS defines a "flat" as the mail class EDDM pieces fall into. Flats have minimum and maximum dimensions, and your printed piece must land inside that window on all three measurements: height, length, and thickness.
The current EDDM flat size requirements are:
A standard 4x6 postcard does not qualify. Neither does a 6x9 postcard. These are letter-class sizes, and EDDM requires flat-class dimensions. The smallest piece that qualifies is sometimes called an "EDDM mini" and measures right at the 6.125 x 11.5 minimum. A more common format is 6.25 x 9 - wait, no, that undershoots. The practical entry point most printers use is 6.5 x 9, which also does not qualify. The true starting point is 6.125 x 11.5.
This surprises a lot of business owners who assumed any oversized postcard would work. If your printer quotes you a "jumbo postcard" that is 6 x 9, ask them specifically whether it meets EDDM flat minimums. If they hesitate, it probably does not.
Why does size matter so much? The post office's automated flat-sorting equipment is calibrated to these dimensions. A piece that is too small passes through incorrectly or jams. A piece that is too large requires hand processing the equipment was not designed for. The rules are not arbitrary; they reflect physical machine tolerances.
Every EDDM piece must carry a specific postal indicia (the printed marking that replaces a stamp and signals postage has been paid). For the EDDM Retail program, the indicia must read:
ECRWSS EDDM Postal Customer
The words "Postal Customer" serve as the "address" because no individual addresses are printed on EDDM pieces. This must appear in the address area on the right side of the mail piece, formatted correctly.
"ECRWSS" is the USPS automation code for "Every Carrier Route Walk Sequence Saturation." It tells the postal system how the piece is classified. If your designer writes anything different, or omits "EDDM" from the indicia block, the piece will not be accepted.
The indicia box must also include the mailer's permit information if you are using a permit, or the standard EDDM Retail wording if you are paying at the counter. Most small businesses use EDDM Retail (paying at the counter), which means the indicia reads exactly as above, with no permit number required.
You cannot simply hand over a loose stack of postcards. USPS requires EDDM pieces to be bundled in stacks of 50 to 100 pieces each, with a facing slip on top of each bundle.
The facing slip must include:
USPS provides a facing slip template through their online EDDM tool. Print them out and fill them in. Then band each one to the top of its bundle. Do not staple, do not tape. A rubber band or paper band is correct.
If you are mailing to multiple routes, each route gets its own set of bundles with its own facing slips. Do not mix routes in one bundle.
The bundling rule exists because the carrier picks up pre-sorted bundles matched to their specific route. They do not re-sort at the office. The bundle you hand in is the bundle that goes on the mail truck, so accuracy matters.
Each EDDM flat piece has a weight maximum of 3.3 ounces. For a standard postcard printed on 100 lb. gloss cover stock, this is not a concern. Where businesses sometimes stumble is when they add features: folded self-mailers with multiple panels, heavier cardstock for a premium feel, or attached items like magnets or seed packets.
A single postcard on standard cover stock runs well under an ounce. A folded brochure printed on heavy stock, with an insert tucked inside, can approach or exceed the limit. If you are designing anything more complex than a flat card, weigh a printed sample before you commit to a full run.
The practical reason weight matters is not just postal compliance. Heavier pieces cost more to print and ship to you (if you are using a mail-house). A piece that barely passes the weight limit on one paper stock may fail if your printer substitutes a slightly heavier substrate. Confirm the paper weight with your printer and ask them to verify the finished piece weight before the run.
EDDM is restricted to advertising and promotional mail. You cannot use it to send invoices, statements, or anything that functions as a personal communication. The content must be the same for every recipient on the route, which is inherent in the no-address-list format.
Certain product categories also face restrictions. Alcohol advertising, tobacco advertising, and content deemed inappropriate for general audiences are subject to additional USPS content rules. If your business is in a regulated industry, review USPS Publication 417 before designing your piece.
EDDM also cannot be used to mail to P.O. boxes only or to commercial routes exclusively in some configurations. When you use the USPS online route selector, routes are labeled as residential, commercial, or mixed. EDDM Retail is limited to residential and mixed routes. If you want to mail to a predominantly commercial route, you may need to explore a different mail class.
A step that trips up first-timers: you must complete an online order through the USPS EDDM Retail portal before you visit the post office. You select your routes, confirm the piece count, and pay online. When you arrive at the post office, you bring your printed, bundled mail and your order confirmation.
If you walk in with boxes of postcards and no online order, the postal clerk cannot accept the mailing. The system is set up so that payment and route selection happen digitally in advance.
This also means you need to know your final piece count before you order. Each route has a published piece count (the number of deliverable addresses), and your print run needs to match. Order confirmation requires you to commit to specific routes and quantities.
The USPS EDDM portal is free to use, and the route selection map shows the piece count for every route so you can plan your print quantity accurately.
EDDM drops must go to the Business Mail Entry Unit (BMEU) or the accepting retail window at the post office that serves the ZIP codes you are mailing to. You cannot drop EDDM at just any post office. It must be the office that handles delivery for those routes.
If you are mailing to routes across multiple ZIP codes, you may need to drop at multiple post offices, or you may be able to consolidate at a single BMEU that accepts mail for a wider area. Call ahead to confirm.
Plan for the drop to take some time. A postal clerk will check your order confirmation and your bundles, and confirm the facing slips match your submitted routes. Bring your order number, be patient, and make sure your bundles are clean and clearly labeled.
A few patterns come up again and again among business owners who have been through the EDDM process:
Getting these details right before you invest in printing is the whole point. The services we offer include walking clients through EDDM preparation so the pieces arrive at the post office ready to go.
The rules are not just operational hurdles. They actually shape what your piece should look like. Because the minimum size is 6.125 x 11.5 inches, you have real estate to work with. A piece that large gives you room to lead with a strong visual and a clear offer while still listing your contact details without crowding.
Understanding what makes the piece itself effective is a separate conversation from compliance, but they are related. A piece that is technically perfect but visually cluttered still underperforms. The post What Makes a Postcard Ad Get Called covers the creative side of what drives recipients to pick up the phone.
And once your mailing goes out, knowing whether it worked requires a system for tracking responses. Before you run your first drop, read How to Tell Whether Your Postcard Actually Worked so you have a measurement plan in place.
Use this before approving any EDDM print job:
If you have questions about any of these steps or want help getting a mailing prepared correctly, the contact page is the fastest way to reach us. And if you are still weighing whether EDDM is the right format for your business, our FAQ covers some of the common decision points in plain language.
EDDM is a genuinely useful tool when you run it correctly. The rules exist to keep the postal system moving efficiently, and once you know them, they are straightforward to follow. Get the specs right before you print, and the rest of the process runs smoothly.
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