To qualify for USPS EDDM Retail, a mailpiece must be a commercial direct mail flat, weigh 3.3 ounces or less, be at least 0.007 inches thick, and meet at least one flat-size trigger: more than 10.5 inches long, more than 6.125 inches high, or more than 0.25 inches thick. It cannot exceed 15 inches long, 12 inches high, or 0.75 inches thick.
2026 EDDM Compliance Matrix
| Requirement | USPS EDDM Retail Rule |
|---|---|
| Minimum size trigger | More than 10.5″ long, or more than 6.125″ high, or more than 0.25″ thick |
| Maximum size | No more than 15″ long and 12″ high |
| Thickness range | 0.007″ to 0.75″ |
| Maximum weight | 3.3 ounces per mailpiece |
| Address format | Local Postal Customer or Postal Customer |
| Postage mark | Approved EDDM Retail indicia |
| Best safe formats | 6.5″ x 9″, 8.5″ x 11″, 6″ x 11″, 9″ x 12″ |
The Gatekeeper’s Rulebook: Why Standard Postcards Fail EDDM Rules
A standard 4″ x 6″ postcard may look like a postcard, but it does not qualify as an EDDM flat. That size is too small to meet the flat-size threshold. If a designer builds a full campaign on a 4″ x 6″ layout, the piece can be rejected before it ever reaches a neighborhood.
This is where USPS mailing rules get unforgiving. Every Door Direct Mail is not just “postcards without addresses.” It is a specific format that must fit the Postal Service’s flat-mail rules.
Mail The Block’s EDDM service helps local businesses avoid these expensive mistakes by aligning the design, print format, route selection, and drop-off prep before the campaign reaches the printer. For more setup guidance, see our Connecticut EDDM service and direct mail postcards pages.
The Dimensional Boundaries: Min vs. Max EDDM Sizes
USPS EDDM sizing requirements are built around qualifying as a flat. To qualify, the mailpiece must exceed at least one of these minimums:
- More than 10.5″ long
- More than 6.125″ high
- More than 0.25″ thick
That does not mean every tiny card is acceptable just because it is printed on heavy stock. The piece still needs to fit within USPS dimensional limits and remain mail-ready.
The maximum EDDM postcard dimensions are also strict:
- No more than 15″ long
- No more than 12″ high
- No more than 0.75″ thick
This is why common EDDM-friendly formats include 6.5″ x 9″, 8.5″ x 11″, 6″ x 11″, and 9″ x 12″. These sizes give local contractors, restaurants, real estate teams, and home service brands enough room for offers, photos, reviews, QR codes, and service-area messaging.
The Weight and Thickness Calculus
EDDM weight limits are generous for most postcards, but they still matter. Each EDDM Retail mailpiece must weigh 3.3 ounces or less. Most single-panel postcards on quality cover stock fall below that cap, but thick folded menus, laminated pieces, booklet-style mailers, and oversized formats should be weighed before the full run is printed.
Thickness is another common failure point. An EDDM piece must be at least 0.007 inches thick. That is why thin flyer paper can create problems. Many campaigns use heavier cover stock because it feels better, survives handling, and meets the physical requirements more reliably.
A safe rule: choose sturdy card stock, verify final trim size, and weigh a finished proof before approving the full order.
The Indicia and Address Block Real Estate
The EDDM Retail indicia is the postage box that tells USPS the piece is being mailed through Every Door Direct Mail. It must appear on the same side as the address area and should be placed in the upper portion of the mailpiece with the mailing label area.
The simplified address usually reads:
Postal Customer
or
Local Postal Customer
Designers should leave clean space for the indicia, address block, return address if used, and any required route or facing-slip workflow. Do not place critical offer text, QR codes, or coupon details where USPS information needs to appear.
For layout support, use an EDDM template download before design begins. This prevents the most common failure: a beautiful mailer with no compliant mailing panel.
Mailpiece Design Compliance Checklist
Before printing, confirm:
- The final trim size qualifies as an EDDM flat.
- The piece is at least 0.007″ thick.
- The finished piece weighs 3.3 oz or less.
- The indicia is included and positioned correctly.
- The simplified address is present.
- The mailing panel is not crowded.
- The artwork uses the final print dimensions, not a resized export.
- Bundling and route paperwork are planned before drop-off.
Why Mail The Block Checks Compliance First
A rejected mailer wastes design time, print budget, campaign timing, and seasonal opportunity. For Connecticut businesses mailing in Hartford, New Britain, Bristol, Southington, Farmington, West Hartford, Avon, Simsbury, and nearby towns, one format error can derail an entire promotion.
Mail The Block’s direct mail process connects creative design, USPS mailpiece design compliance, route targeting, and campaign execution so local businesses can focus on the offer instead of postal guesswork. View our pricing, see campaign examples, or contact Mail The Block before sending artwork to print.
Build the Campaign Right Before It Hits the Press
EDDM can be one of the simplest ways to reach every home on a postal route, but the physical mailpiece rules are not flexible. Size, thickness, weight, indicia, and address block placement need to be right before a single box is printed.
Avoid the trash can. Start with a compliant format, proof the mail panel, and let Mail The Block help prepare an EDDM campaign that is built to pass the gatekeeper.