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Mail guides

How physical mail actually works — what Certified Mail proves, how long delivery really takes, and what to do when a letter comes back. Written from the same USPS rules and provider behaviour the product is built on.

Certified Mail

Proof of mailing, tracking, cost, and when it actually holds up.

What is a USPS Certificate of Mailing?

A USPS Certificate of Mailing proves you mailed something on a given date — it does not track or prove delivery. Here is what it covers, what it costs, and when…

How much does certified mail cost?

USPS Certified Mail costs $6.37–$9.28 in postage and fees alone at the counter. Here is what it costs at the counter and what it costs to have it printed and mailed for you, plus First-Class and Priority.

What does a Certified Mail letter look like?

A labeled example of a Certified Mail envelope and letter — the green sticker, the tracking barcode, and the parts of the letter itself — plus real templates to…

USPS Certified Mail tracking

How to track USPS Certified Mail, what each scan means, how long it takes, and how to get the electronic Return Receipt as proof of delivery.

How to send certified mail

Two ways to send USPS Certified Mail: fill out PS Form 3800 at the post office and keep your green card, or skip the trip and send it online for $12.99 all-in.

What is proof of mailing?

Proof of mailing is documentation that you sent something on a given date. USPS offers three ways to get it, starting at $1.99 — here is which one fits what you…

What is proof of service, and can you do it by mail?

Proof of service shows you properly notified a party in a legal proceeding — not just that you sent something. Here is how Certified Mail with electronic Return…

Send Certified Mail online

Send USPS Certified Mail online in about 2 minutes: upload your document, we print and mail it with proof of mailing and tracking. $12.99 all-in, $14.99 with…

What is Certified Mail?

Certified Mail is a USPS service that proves you mailed something and tracks it to delivery, with an optional signed delivery record. Here is what it is, and…

Sending mail

Getting a document printed, stamped, and into the mail stream.

USPS & delivery

How the mail system behaves once a piece leaves your hands.

Business Reply Mail: how it works and who it's for

Business Reply Mail lets customers mail something back to a company without a stamp, and the company pays postage only on what comes back. Here’s the mechanism,…

What happens to a deceased person's mail?

Mail keeps arriving at a deceased person\'s address because USPS has no automatic way to know. Here is what a family member or executor can do about it, gently…

How long does mail take to arrive?

First-Class Mail takes 3–5 business days, Priority Mail 1–3 days, and Certified Mail travels at First-Class speed (3–5 days) despite the extra tracking. Here is…

International mail & Global Forever stamps: what you need to know

What a Global Forever stamp is, how international mail differs from domestic mail, and where to send letters abroad today (paperplane is US-domestic only for now).

Mail Insurance Explained: When It's Worth Adding

Certified Mail proves a letter was mailed and delivered — it does not insure the value of what\'s inside. Here is what USPS Insurance actually covers, and when…

Mail theft: what to do if your mail was stolen

How to tell if your mail was stolen, how to report it to the USPS Postal Inspection Service, and how to protect anything sensitive with tracked mail going forward.

Media Mail rates & restrictions: what you can and can’t send

What USPS Media Mail actually covers, why it’s restricted, and why it’s never the right choice for a letter or document — those ship First-Class, Certified, or…

PO Box rental basics

What a PO Box actually costs, how to rent one at USPS, what can and can’t be delivered there, and how to mail a letter to a PO Box address.

Return to sender, refused, or unclaimed Certified Mail: what it means legally

A refused or unclaimed Certified Mail piece often still counts as valid legal notice in many states, because your tracking record shows a properly addressed…

Undeliverable & dead mail: what happens when USPS can’t deliver

What makes a letter "undeliverable as addressed," what USPS does with it afterward — including the Mail Recovery Center — and how to stop it from happening to…

How does USPS Hold Mail work?

USPS Hold Mail pauses delivery to an address for up to 30 days so mail waits at the post office instead of piling up. Here is how to request it, and what it…

USPS Informed Delivery, explained

What USPS Informed Delivery is, how the free daily email digest works, how to sign up, and why it pairs well with a Certified Mail tracking number.

How does USPS mail forwarding work?

USPS mail forwarding redirects mail addressed to your old address for up to 12 months. Here is how to set it up, what it costs, and why you still need to mail…

Missing mail: how to file a USPS claim

What to do when a letter never arrives — how to file a USPS Missing Mail Search Request, why Certified Mail is not insurance, and what a realistic timeline looks…

What is a mailing list?

A mailing list is just a set of names and addresses you send the same piece of mail to. Here is what belongs in one, how to keep it clean, and how to send to it…

For developers & agents

Mailing from code, CRMs, and AI agents.

How AI agents mail physical letters via MCP

How the paperplane MCP server lets an AI agent quote, send, and track real USPS mail: the two-step quote→send confirmation pattern, error handling, and the REST…

Automate compliance mail from your CRM or support tool

A build-your-own pattern for triggering certified mail from Salesforce, HubSpot, Zendesk, or an internal tool via the paperplane REST API — trigger conditions,…

Use paperplane in Grok

Add paperplane as a custom MCP connector in Grok (or via the xAI API) and Grok can quote, send, and track real USPS letters — with a free sandbox to test first.

Use paperplane in Lindy

Connect paperplane to Lindy as an MCP server and your Lindy agents can quote, send, and track real USPS letters — no API key, free sandbox mode for testing.

Use paperplane in Gumloop

Connect paperplane to Gumloop as a custom MCP connector and your flows and agents can quote, send, and track real USPS mail — free sandbox mode, no API key.

Use paperplane in Dust

Add paperplane as a remote MCP server in your Dust workspace and any Dust agent can quote, send, and track real USPS letters — free sandbox, no API key.

Use paperplane in n8n

Install the real n8n-nodes-paperplane community node and any workflow can quote, send, and track real USPS letters — three operations, a confirmation-token safety contract, sandbox on by default.

Use paperplane in Pipedream

Run the real paperplane Pipedream component — Quote Letter, Send Letter, Get Letter Status — in your own workflow via the Pipedream CLI, ahead of its public app-directory listing. Free sandbox, no auth.

Use paperplane in Microsoft Copilot Studio

Add paperplane as a Model Context Protocol tool in Microsoft Copilot Studio via the built-in MCP onboarding wizard, and your agent can quote, send, and track real USPS letters — no API key, free sandbox.

Send mail from LangGraph, the Vercel AI SDK, or OpenClaw

Three short, real code snippets that attach paperplane's MCP server to a LangGraph agent, a Vercel AI SDK app, or OpenClaw's CLI — plus the plain REST fallback for any framework.