Send a certified letter
How to send a certified letter online — without the Post Office
Certified Mail is the standard way to prove that a letter was sent and what happened to it. You no longer have to print it, fill in the green forms and wait in line. Here is what it costs in 2026, what you need, and the fastest path: preparing it from the AI you drafted it with.
Prepare my letterConnect your assistant
This page explains the job. Prepare my letter starts it: sign in with your email address (a one-time link, no password), then paste or attach the letter. Live mailing is open to invited accounts only for now; ask at support@piloxa.com.
The short answer
- Finish the letter. Make sure the recipient’s legal name and street address are exact.
- Either paste the letter into Piloxa (sign in with your email, press Paste the letter text) — or, if your assistant is connected, tell it: “Prepare this letter for Certified Mail with return receipt to [recipient].”
- Open the review link. Read every page as it will be printed, confirm the address the Postal Service recognized, and look at the single total.
- Authorize with your card. A printing partner mails it the next business day, USPS Certified with electronic return receipt.
- Come back any time — or ask your assistant — for the tracking events, the delivery scan and the signature.
What it costs in 2026
| Item | USPS price |
|---|---|
| First-Class letter postage, 1 ounce | $0.78 – $0.82 |
| Certified Mail fee | $5.55 |
| Electronic return receipt (signature as a PDF) | $2.91 |
| Certified with electronic return receipt, at the counter | $9.24 – $9.28 |
Today a one-page letter sent Certified with the electronic return receipt is $16.17 all in — printing, the envelope, postage, the certified fee and the return receipt. Longer letters cost a little more. The exact total is on the review page before you pay, and there is no second charge afterwards. USPS figures above are rates effective July 12, 2026.
What you need
- The letter, finished. Piloxa renders it as a clean US-Letter PDF, or you upload a PDF you already have.
- The recipient’s exact name and street address. For a company, use its legal name and the address for legal notices — often the registered agent, which you can find on your Secretary of State’s business search. Piloxa checks the address against the USPS database before you pay.
- Your return address. It is printed on the envelope and on the return receipt.
- A card. One charge, shown in full on the review page.
No connector needed: paste the letter
Drafted the letter in a chat and only want the fastest way out of it? Mail a letter your AI wrote is that page.
Any letter from any assistant can be mailed without installing anything. Copy the finished letter out of the chat, open Piloxa, sign in with your email address (a link is sent, no password to invent), press Prepare my letter, then Paste the letter text. Fill in who it is from and who it goes to, and Piloxa lays the letter out as a clean PDF. You can still change the wording on the page. You see the pages, the USPS-checked address and one total before you pay. Piloxa cannot read your chats: what you paste is all it sees.
If you already have the letter as a PDF, attach it instead — it is kept byte for byte and never rewritten.
Connecting your assistant to Piloxa
Piloxa is a custom connector (a “custom MCP server”, in the assistants’ own words). Its address is https://piloxa.com/mcp. Adding it takes about a minute and gives the assistant exactly one ability: to prepare a certified letter for your review. It cannot mail or charge anything.
Claude
Open claude.ai → Settings → Connectors, choose Add custom connector, name it “Piloxa”, paste the address, and continue. The connector shows one tool, “Prepare a certified letter for review”.
ChatGPT
Turn on Developer mode in ChatGPT’s settings (it sits under the connectors or plugins section, marked “advanced”), then choose Create to add a connector: name “Piloxa”, the address above, authentication “No Auth”.
Gemini
Custom apps are part of Gemini Spark, which needs a Google AI Pro or Ultra subscription on a personal Google account, in the United States, in English; work and school accounts do not offer it. In the Gemini web app open Settings → Connected apps → Custom apps, choose Add a custom app and paste the address. Once connected it is available in the mobile app too.
Perplexity and Grok
Both accept a custom remote connector by address. In Perplexity, an organization’s administrator may need to allow custom connectors first; choose authentication “None”. In Grok, open Connectors and add your own server with the address above. Neither has been tested end to end by us yet.
Each assistant shows a warning that the connector is unverified. That warning is about the connection itself. Piloxa’s only tool returns a review link; a signed-in person has to approve and pay on the site before anything moves.
What each assistant can hand over
There are three ways the document reaches the review page. Which one your assistant can use depends on what it can actually read — a file name it mentions is not a file it can send. The table says what has been tested, not what should work.
| How the document arrives | Claude | ChatGPT | Gemini |
|---|---|---|---|
| The letter text, written in the chat — Piloxa lays it out as a PDF you can still edit on the review page | Tested | Connected, not yet tested end to end | Not tested |
| A finished PDF, sent as the file itself — kept byte for byte, never rewritten | Tested from Claude Code and Cowork, where the file is on disk; not tested from a file attached in the claude.ai chat | Tested with a PDF attached to the chat (ChatGPT reads the bytes itself; on the first try its copy did not match the file's fingerprint, Piloxa refused it, and the retry arrived intact) | Not tested |
| You attach the PDF yourself on the review page — recipient, service and price already filled in | Tested | Tested | Not tested |
When the file cannot be sent, the assistant is told to say so and to prepare everything else; you attach the PDF once on the review page. Nothing you already told the assistant is asked for again. A document that arrives damaged, password-protected, or with a fingerprint that does not match what the assistant stated is refused, and the assistant is told why.
Send this letter from the AI you already use
Draft your letter with ChatGPT, Claude, Gemini or any assistant that supports custom connectors, then say:
“Prepare this letter for Certified Mail with return receipt.”
Piloxa is the connector the assistant calls. Its address is https://piloxa.com/mcp. The assistant cannot mail anything: it hands you a review link. You open it, read the exact pages that will be printed, check the recipient, see one total, and authorize with your card. Only then does the letter leave. Afterwards the document, its fingerprint, the address, every tracking event and the signature stay together as one record — and any assistant you connect can read it back to you.
Status, September 2026: Piloxa is opening in stages. Review, address checking and pricing work today; live mailing is switched on for invited accounts first. To be invited, write to support@piloxa.com.
Doing it yourself instead
You can still do this at a Post Office counter: print the letter and keep an identical copy, fill in PS Form 3800 (the Certified Mail label), request the electronic return receipt, pay, and keep the stamped receipt and the tracking number somewhere you will still find them in two years. The guide to what Certified Mail proves walks through it and lists what to keep.
Common questions
Can I send Certified Mail to a P.O. Box?
Yes. Certified Mail is delivered to P.O. Boxes; the box holder signs when picking it up. Credit bureaus and many companies list P.O. Box addresses for disputes and notices.
How long does delivery take?
Certified Mail travels as First-Class Mail, typically two to five business days within the United States. The tracking record shows each step, including any delivery attempt, refusal or return.
What is an electronic return receipt?
The Postal Service emails a PDF with the recipient’s signature (or the delivery record) instead of mailing back the green card. It costs $2.91 against $4.65 for the card, arrives faster, and cannot be misplaced. Piloxa stores it with the letter.
What if the recipient refuses the letter?
The tracking record documents the refusal or the unclaimed return. For most legal notices, proof that the notice was properly sent to the correct address is what matters, and a documented refusal shows exactly that.
Does Piloxa read my letter?
The letter is rendered, fingerprinted and printed by the mail partner. It is not used for anything else, and it is never shared with an assistant unless you connect one to your own record.