How to send a debt validation letter by certified mail, with AI

Have Claude or ChatGPT draft a debt validation letter and mail it to the collector by USPS certified mail with a return receipt, so you have proof of the date. From $8.61.

When a debt collector contacts you about a debt you don't recognize, or an amount that looks wrong, you can ask them in writing to prove it. That's a debt validation (or dispute) letter. The timing matters, so you want a record of exactly when you mailed it. Certified mail gives you that.

With Mailsnail connected, your AI assistant can draft the letter and mail it certified in one go.

Connect once

Add this URL to Claude, ChatGPT or any app with MCP connectors, then sign in:

https://api.mailsnail.dev/mcp

The setup page has steps for each app.

Ask for the letter

Have the collector's notice in front of you and tell the assistant what it says:

A collector called Northline Recovery sent me a notice dated October 20 saying I owe $1,312 on account 55-20931 for an old phone bill. I don't recognize it. Draft a short letter disputing the debt and asking them to validate it: the original creditor, the amount and how it was calculated, and proof they're allowed to collect it. Don't admit the debt or offer to pay. Mail it to their address, PO Box 4410, Tampa FL 33601, by certified mail with an electronic return receipt, and show me the proof first.

Keep the letter brief. It should identify the account, say you dispute it, and ask for validation. It shouldn't explain your finances, admit anything, or promise payment.

What the assistant does

  1. verify_address confirms the collector's mailing address is deliverable. Free.
  2. preview_letter returns a proof PDF and the exact price, with nothing charged.
  3. You check the proof: your name, the account number, and that nothing in it admits the debt.
  4. send_letter mails it certified, with the return receipt you asked for, and returns a receipt token.

Proof of mailing and delivery

Later, ask "has my letter to Northline been delivered?" with the receipt token. get_letter returns the USPS tracking number, the latest scan, and for an electronic return receipt a link to the signature PDF. Keep those with the collector's notice.

Service From a balance One letter by card
Certified $8.61 $8.83
Certified + electronic return receipt $11.64 $11.83
Certified + green card $14.27 $14.42

Where to learn more

The Consumer Financial Protection Bureau's site, consumerfinance.gov, explains your rights with debt collectors and has sample letters. If a collector keeps contacting you after you dispute, or you're being sued, contact a legal aid office or a consumer lawyer.

Mailsnail prints and mails what you approve. We don't give legal advice.

Related guides

FAQ

When should I send a debt validation letter?

Under the federal Fair Debt Collection Practices Act, you can dispute a debt in writing within 30 days of the collector's first notice to you, and the collector then has to stop collecting until it sends verification. Send it as soon as you can, and keep proof of the mailing date.

Why certified mail?

Certified mail gives you a USPS record of the date you mailed the letter, and a return receipt shows when it was delivered and who signed. If the collector later says they never got it, you have proof.

How much does it cost?

For a one-page letter from a prepaid balance: $8.61 certified, $11.64 with an electronic return receipt, $14.27 with the green-card return receipt. Paying for just that letter by card costs $8.83, $11.83 or $14.42.

Is this legal advice?

No. Mailsnail prints and mails the letter you approve. For questions about your rights, the Consumer Financial Protection Bureau (consumerfinance.gov) has free sample letters and guidance, and legal aid offices can help.

Connect Mailsnail to your agent

Nothing to install — it's a hosted server you sign into. In Claude Code:

bash
claude mcp add -t http mailsnail https://api.mailsnail.dev/mcp

Then run /mcp and choose Authenticate. Clients that take a JSON config use the url form:

mcp.json
{
  "mcpServers": {
    "mailsnail": {
      "url": "https://api.mailsnail.dev/mcp"
    }
  }
}

Per-client steps, and the self-hosted path, are at /setup.

← All guides