Mailing specifications
PostalForm mailing limits and provider routing
PostalForm chooses an eligible print-mail route from the destination, sender, document page count, print mode, mailing service and enabled providers. These are the application's configured route limits, not a guarantee that every provider is available for every address. Validate the actual order before relying on a maximum.
Published Oct 15, 2026
How many pages can PostalForm mail?
PostalForm checks the document against the selected provider and mailing service before checkout. The configured general routes include up to 199 single-sided or 398 double-sided document pages, but Certified Mail and international routes have separate limits. The generated address page, physical sheet count and final quote must be considered separately.
Document pages, printed pages and physical sheets
- Document pages are the pages in the submitted or generated document. Routing limits below use this count.
- Billable pages include the address page when the selected route adds one. A one-page document can therefore have two billable pages.
- Physical sheets depend on printing mode and how the provider inserts the address sheet. Duplex does not make a separate cover sheet disappear.
- For First-Class letters, a one-page document normally adds an address page. Lob duplex letters use a separate cover sheet; other routes may place the document on its reverse. Use the canonical pricing matrix for examples.
- USPS First-Class, Certified Mail and Return Receipt are distinct choices. Return Receipt is an optional proof service; it does not increase the route's document capacity.
Configured U.S. document limits
| Route | General single-sided limit | General double-sided limit | Certified Mail limit | Scope |
|---|---|---|---|---|
| Lob | 59 document pages | 118 document pages | 59 single-sided / 118 double-sided | Eligible U.S. First-Class letters |
| PostGrid | 199 document pages | 398 document pages | 6 single-sided / 12 double-sided | Separate Certified limits apply |
| Click2Mail | 99 document pages | 198 document pages | No general consumer Certified route promised here | Eligible Priority / Rush Express mail; product availability depends on the checkout path |
The claim that a Certified letter exceeding Lob's limit automatically switches to PostGrid's 199/398-page capacity is incorrect. Those are PostGrid's general limits; its configured Certified capacity is lower. If no eligible route supports the chosen document and service, validation rejects the combination. Do not split a legal packet or change a required mailing method merely to bypass a limit.
Provider-specific enterprise or Projects products can have different supported services. Use that product's API and quote rather than transferring a limit or capability from another PostalForm checkout path.
International mail and postcards
| Capability | Main constraint | Reference |
|---|---|---|
| International document mail | Supported destination, return address, local format, file size and country-specific page limit | International mailing |
| PinGen Fast | Offered only for eligible destinations and documents | Delivery options |
| Postcard PDF | Exactly two pages with the selected bleed canvas | Postcard PDF specifications |
| International Lob postcard | 4x6 size and U.S. return address |
Postcards |
| Workflow form API | Published single-mailpiece form, active required fields and attachment limits | Machine form schemas |
Do not apply the general maximum to every international destination. PinGen page limits vary by country and its PDF size limit is 8 MB. The browser's 100 MB upload ceiling does not override a smaller provider limit.
Validate before quoting or paying
For a browser order, upload or generate the document and inspect its preview, addresses, available mailing services and total. For an agent, call POST /api/machine/orders/validate or POST /api/machine/mpp/orders/validate using the complete proposed order. A successful validation checks the proposed input; it does not pay for or send mail.
Use the returned errors to fix the document or select an authorized alternative. After payment, retain the order ID for status retrieval. A provider handoff or postal acceptance event is not proof of delivery.