Send outbound business mail
via API + MCP
Agents can prepare and submit documents, send them to addresses, select a mail class, and run sandbox tests before initiating a live outbound print-and-mail order. Everything is tracked, photographed, and searchable—from delivery progress to confirmation.
Certified Letters
Legal proof of delivery for demand letters, compliance notices, and inbound-mail responses.
Demand Letters
Debt collection notices with certified tracking and proof of service for compliance.
Legal Notices
Compliance notices, cease-and-desist letters, and regulatory responses on deadline.
Real Estate Offers
Acquisition letters, LOIs, and follow-ups from forwarded owner packets or offer mail.
Postcards & Outreach
Permit-triggered postcards, before-and-after mailers, and visual direct mail campaigns.
Property Notices
Lease violations, rent reminders, move-out notices, and cure-or-quit letters.
Business Letters
Invoices, contracts, statements, and partnership letters - printed and mailed from code.
Insurance Claims
Dispute letters, supporting documentation, and certified negotiation correspondence.
Government Filings
Permit applications, license renewals, correction notices, FOIA requests, and regulatory replies.
Every piece of mail,
structured instantly
Your webhook receives a small, signed JSON event for every item: the sender line read from the envelope, letter or package, page counts, and two URLs. Page text and images never travel in the payload; your agent fetches them with its API key.
To send, call send_outbound_mail over MCP, or POST /v1/mail, with a document, a recipient and a mail class.
- inbound.received
- inbound.action.requested
- inbound.action.completed
- inbound.pages_ready
- inbound.keywords_matched
- mail.pending_approval
- mail.submitted
- mail.ready
- mail.mailed
- mail.delivered
{"event_type": "inbound.received","item": {"reference": "SAMPLE-09941F955E23","kind": "letter","sender": "Mojave Land Partners","status": "received","pages": { "envelope": 1, "contents": 0 }},"api_url": "https://mailbox.bot/api/v1/inbound-items/b434…f6a6","pages_url": "https://mailbox.bot/api/v1/inbound-items/b434…f6a6/pages"// 9 more fields in the full payload}
{"document_filename": "notice.pdf","document_base64": "JVBERi0xLjcK…","mailbox_md_version": 3,"recipient_name": "State of Delaware","recipient_line1": "401 Federal Street","recipient_city": "Dover","recipient_state": "DE","recipient_zip": "19901","mail_class": "certified_return_receipt","requires_approval": true// also: dry_run, max_cost_cents, metadata}
“Mailbox.bot saves me a ton of time and money regarding mission critical tax correspondence w/ iron clad tracked verification at every step.”
Founder & CEO
Prime Accounting Solutions
Culver City, CA
“My office admin agent ‘Clawdius’ (yes that’s his real name) initiates outbound compliance mail, permit filings, and follow up which saves us hours every month as a contractor.”
Los Angeles, CA
You submit documents & letters
We print & handle the post office
Every outbound letter is printed, stuffed, stamped, and mailed by trained facility staff. Fulfillment photos verify every piece. You get structured webhooks at every stage — no post office visits, ever.
Frequently
asked
questions
Get your limited spot for a physical mailing address at location #1.Location #2 and #3 will be in Nevada and Utah.
Location #1 is our staffed Manhattan Beach, California facility. Each mailbox is a virtual mailbox at a real street address, not a PO Box. Create your account, verify your phone number and choose the mailbox option; your mailbox number is assigned after USPS Form 1583 verification.
curl -X POST https://mailbox.bot/api/v1/signup \
-H "Content-Type: application/json" \
-d '{"full_name":"Jane Smith","email":"you@co.com","password":"s3cure-pass","needs":"a mailing address for my agent, plus outbound mail"}'Agent-callable account signup: no CAPTCHA and no bearer token on this endpoint. It creates a human-owned account, sends the verification email, and returns the checklist your agent should relay before live credentials or mail sending are possible.
mailbox.bot issues receiving addresses and handles packages at the staffed Manhattan Beach, CA facility (2100 N Sepulveda Blvd STE 28, Manhattan Beach, CA 90266). To get a mailing address #, call /api/v1/mailing-address-requests first and pass the returned lead_id into signup. Then connect through LangChain, CrewAI, LlamaIndex, Vercel AI SDK, OpenAI Agents SDK, MCP, A2A, or the REST API.