PostalForm mailing resources

• Developer Mail API for Letters, PDFs, and Postcards — Updated August 31, 2026. PostalForm Projects is a developer mail API for adding physical mail to an app.
• Mail Letters With an API — Updated August 31, 2026. PostalForm lets an app or AI assistant prepare a reviewable physical-mail draft from text, HTML, Markdown, RTF, or PDF.
• How to mail a letter online by country — Updated August 29, 2026. PostalForm can print and mail a PDF to every country listed below.
• Certified Mail forms: PS Form 3800, 3811, and 3817 — Updated August 10, 2026. The Certified Mail form most people need is USPS PS Form 3800, the Certified Mail receipt and barcode label used for domestic Certified Mail.
• PostalForm mailing guides — Updated August 10, 2026. Use these guides when you need to prepare a letter, form, notice, or document packet and send it through the appropriate mailing provider without printing at home.
• Send Certified Mail online — Updated August 8, 2026. Certified Mail is a USPS add-on that documents mailing and delivery or attempted delivery.

• Best way to mail a PDF online — Compare the choices that matter when a finished document needs to become physical mail.
• Certified Mail online services and alternatives — Choose between a managed print-and-mail service, an office workflow, and a Certified Mail label tool.
• How to mail a letter from your phone — Prepare, review, and send a letter without a computer, printer, envelopes, or stamps.

• How long Certified Mail takes — Separate production time, USPS transit estimates, delivery attempts, and Return Receipt timing.
• Certified Mail cost breakdown — Understand postage, USPS extra-service fees, and the price of an online fulfillment service.
• Certified Mail Return Receipt — Decide when a signature record is useful and how electronic and hard-copy receipts differ.
• Certified Mail vs. Registered Mail — Compare proof, handling, insurance, and the jobs each USPS service is designed for.

• Demand letter resources — Payment demands, final notices, contractor claims, and guided letter workflows.
• Turn an unpaid invoice into a Certified Mail demand — Build a documented payment-demand packet from an invoice.
• Mail an invoice online — Send a finished invoice or statement without handling printing and envelopes in-house.
• Landlord notice workflows — Prepare and mail common property-management notices and packets.
• Bulk mail — Personalize and send one document to many recipients from a CSV.

PostalForm provides document and mailing tools, not legal advice. Confirm the recipient, deadline, required delivery method, and governing rules for any legal or official notice.

• Guided forms catalog — Complete, preview, and mail supported government, dispute, tax, and notice workflows.
• Dispute mail — Credit-report, billing, debt-validation, and written dispute resources.
• Tax forms and letters — Mailing workflows for supported IRS forms, elections, and responses.
• Court forms and filings — Prepare printable packets and follow the receiving court's filing instructions.
• Consumer complaint and credit-report guides — Written requests, disputes, and documentation-oriented workflows.

• PostalForm Projects — Add letters and postcards to an application with test and live API keys, final-price quotes, idempotent sends, tracking, and signed webhooks.
• Hosted checkout and MCP mail flows — Create reviewable drafts and return checkout URLs when a person should approve and pay.
• Send physical mail from an AI agent — Choose a safe human-review or explicitly authorized machine-payment path.
• Developer documentation — Review the available REST, MCP, agent, discovery, and payment surfaces.

PostalForm Projects can also be provisioned through Stripe Projects with a single command.

See supported countries and local mailing options for letters sent to the United States, Canada, Austria, Belgium, Switzerland, Germany, Spain, France, the United Kingdom, India, Luxembourg, and the Netherlands. Available tracking, signature, registered, and expedited options vary by destination.

• Mailing price calculator — Estimate fulfillment cost by page count, print settings, destination, and delivery options.
• Free PDF editor — Add text, signatures, images, or corrections before downloading or mailing a document.
• Merge PDFs — Put a letter, form, and exhibits into one ordered packet.
• Split a PDF — Extract the pages you need before sending.
• Delivery times — Review production and carrier estimates before choosing a service level.

• PostalForm online mailing data: H1 2026 order patterns — Aggregate, privacy-preserving patterns from paid PostalForm orders.
• Best online print-and-mail services — Compare providers by workflow rather than treating every service as interchangeable.
• PostalForm alternatives — Decide which type of mailing product best fits a one-off sender, team, or developer.
• Mailform alternative — Compare browser-based document mailing workflows.
• Click2Mail alternatives and LetterStream alternatives — Compare consumer-friendly and business-mail options.

This page is intentionally curated. For the complete machine-readable list of public articles and mailing guides, use the PostalForm article index.