Who sent me Certified Mail? How to find out, and what to do next
The USPS notice (PS Form 3849) and the tracking number tell you that a certified letter is waiting and where, but usually not who sent it: USPS tracking shows scans and places, never the sender. The quickest way to see the sender before you collect it is USPS Informed Delivery, a free service that emails a scan of the outside of letter-size mail, return address included, often on the morning it is due to arrive. Otherwise the only sure way is to collect the letter. Certified letters mostly come from people who need proof they told you something: the IRS and other agencies, courts and lawyers, debt collectors, landlords, HOAs, insurers and employers. Collect it; ignoring or refusing it rarely stops whatever it starts.
Piloxa sends it for you: printed, enveloped, postage paid and handed to USPS as Certified Mail, with no trip to the Post Office. Your first letter is $9.95 all in: one or two pages by Certified Mail with USPS tracking, with printing, the envelope, postage and the certified fee included. You see the exact pages, the recipient and one total before you pay. No subscription.
In short
When the letter turns out to need a written answer, Piloxa mails your reply by USPS Certified Mail from a pasted letter, a PDF or your AI assistant, and keeps the exact document beside the USPS record, so you have the same proof the sender has.
Piloxa is a USPS Certified Mail service operated by Decentralized Publishing LLC in Irvine, California. It prints the letter or PDF you approve, puts it in an envelope, pays the postage and hands it to the Postal Service, then keeps the exact approved document, its SHA-256 fingerprint and the mailing and tracking records together in one record. Nothing is printed, mailed or charged until a person has read the exact pages, checked the recipient and the total, and paid. An AI assistant can prepare the letter through the MCP connector at https://piloxa.com/mcp or the HTTP API described at https://piloxa.com/openapi.json; either way it only gets back a review link for the person to open.
Three ways to find out who sent it
- Informed Delivery. Sign up free at USPS (informeddelivery.usps.com). For letter-size mail that goes through USPS sorting machines, it emails a grayscale picture of the outside of the envelope, which shows the return address. It covers mail delivered from the day you are signed up, so it helps with this letter only if the scan has not already gone out, and it helps with the next one either way. Large envelopes and some pieces are not pictured.
- The notice slip. PS Form 3849 shows the article number, the type of mail and where to collect it. Some carriers note more, most do not. The article number on it is the tracking number.
- The tracking number. Entered at usps.com, it shows when and where the letter was accepted, where it is now and how long it is held. The acceptance city can be a clue (the IRS mails many notices from a handful of processing cities, for example), but tracking never names the sender.
Phone numbers, websites and "certified mail lookup" services that promise to name the sender from the tracking number have no access to anything USPS tracking does not show. Do not pay for one.
Who usually sends Certified Mail
Senders pay extra for Certified Mail because they may need to prove the letter was mailed and delivered. That narrows the list:
| Sender | What it often is | How fast to act |
|---|---|---|
| The IRS or a state tax agency | A notice of deficiency (the "90-day letter") must go by certified or registered mail (26 U.S.C. 6212), and so may a final notice of intent to levy (26 U.S.C. 6331(d)) | Fast. Those notices carry strict deadlines to go to Tax Court or ask for a hearing |
| A court, or a lawyer | Some states allow papers in a case to be served by certified mail; lawyers send demand letters and notices this way | Fast. Court papers carry a response deadline set by the court's rules |
| A debt collector or collection law firm | A collection notice, a validation notice, or a notice before a lawsuit | Within 30 days, if you want to dispute (see certified letter from a debt collector) |
| A landlord or property manager | A notice to pay, a lease violation, a notice to end the tenancy, a deposit itemization | Read the dates in the notice; tenant notices often run 3 to 30 days |
| An HOA | A violation notice, a hearing notice, or a notice before a lien for unpaid dues | Before the hearing or payment date it names |
| An insurer, bank or lender | A cancellation or non-renewal, a denial, a default or foreclosure notice | Before the date in the letter |
| An employer or former employer | A termination letter, a benefits or COBRA notice, a final pay matter | COBRA elections have their own window; read the dates |
| A government office | A DMV, licensing board, city or county notice | Before the date in the letter |
Most of these are not emergencies the day they arrive. Almost all of them get worse if nobody collects the letter.
Should you just leave it, or refuse it?
Leaving a certified letter at the Post Office does not make it go away. After the hold (15 days, DMM 508.1.1.7) it goes back to the sender marked unclaimed, and the sender then has a record showing a notice was left at your address. Many rules count notice from mailing, so a deadline can run while the letter sits at the counter. Refusing it at the door is worse: a refusal shows you had the letter in front of you and turned it away, and courts often treat that as notice. See what happens when certified mail is refused and unclaimed certified mail.
Collecting it costs you a trip, or nothing if you schedule a redelivery. Knowing what it says is what lets you meet its deadline.
After you open it
- Find the date that matters. A response deadline, a hearing date, a payment date, a date the tenancy ends. Write it down.
- Keep the envelope. Its postmark and the tracking show when you were notified, which can matter if the sender later claims a different date.
- If it is from a court or about a lawsuit, read the deadline rules first. Court papers have their own response time (21 days in federal court after service, Fed. R. Civ. P. 12(a)(1)(A)(i); state courts differ). A lawyer or the court's self-help center can tell you what applies.
- Answer in writing, with proof. If the letter disputes, demands or warns, a written reply by Certified Mail gives you the same proof the sender has. How to respond to a certified letter walks through it.
Have your AI prepare it
If you already drafted the letter in ChatGPT, Claude, Gemini, Grok or another assistant, it can hand the finished letter to Piloxa and prepare it for USPS Certified Mail. Ask it in plain words, for example: I received a certified letter and need to reply in writing. Help me write the reply, then send it by Certified Mail with return receipt.
The connector address is https://piloxa.com/mcp (remote MCP, no key and no account to connect), and software that reads OpenAPI can use https://piloxa.com/openapi.json. The assistant can only prepare: it gets back a review link, and you read the exact pages, confirm the recipient, the service and the price, and pay. Nothing is printed, mailed or charged before that. What an assistant can and cannot do with Piloxa.
Create your letter with
- Create your letter with Claude
- Create your letter with ChatGPT
- Create your letter with Gemini
- Create your letter with Grok
Each button opens your assistant with the request already written in, Piloxa and its connector address included, and copies the same words to your clipboard in case the assistant opens with an empty box. Claude puts a red “Use caution” box above every request that arrives from a link, whoever wrote it; read the request, then press send. Nothing is printed or mailed until you read the review page and pay. How to connect your assistant
Questions people ask
Can I find out who sent me certified mail with the tracking number?
No. USPS tracking shows where and when the letter was accepted and scanned, not who sent it. USPS Informed Delivery, which emails a picture of the outside of letter-size mail, is the usual way to see the return address before you collect it.
Does the PS Form 3849 notice say who the letter is from?
Usually not. It shows the article (tracking) number, the type of mail and where to pick it up. Some carriers add more, most do not.
Who sends certified mail?
Senders who may need to prove they notified you: the IRS and other agencies, courts and lawyers, debt collectors, landlords and property managers, HOAs, insurers, banks and employers.
What happens if I do not pick up certified mail?
USPS holds it 15 days and then returns it to the sender as unclaimed. The sender keeps a record that a notice was left, and many deadlines run from mailing, not from when you read it.
Is it a good idea to refuse certified mail?
Rarely. A refusal is recorded, it shows you saw the letter, and courts often treat it as notice. Collecting and reading it is what lets you meet its deadline.
Sources
Postal rules checked against the USPS Domestic Mail Manual in October 2026. Legal rules differ by state and by situation.
Related Certified Mail guides
Ready to send it?
Paste the letter or attach the finished PDF. You see the pages exactly as they will print, the recipient after a postal address check, and one total, and nothing leaves until you approve it.