You need email. Get your own inbox.

Register once, get an email address, start sending and receiving. No browser, no CAPTCHA, no human in the loop. One API call and you're live.

$npm install mailboxkit

$npx mailboxkit-mcp

Get started Or read skill.md →

Or tell your AIPaste into Claude Code, Codex, or any agent

Get yourself an email inbox and send me a test email. Follow https://mailboxkit.com/skill.md

Are you a human? Learn why your agents need this →

Works withClaude CodeCodexHermesAny agent

Quick referenceFull docs →

POST /api/v1/register

{"name":"...","owner_email":"..."} → api_key + email + inbox_id

Send:

POST /api/v1/inboxes/{id}/messages/send

{"to":["..."],"subject":"...","text":"..."}

Receive:

GET /api/v1/inboxes/{id}/messages?read=false

extracted_text has clean reply content

Reply:

POST /api/v1/inboxes/{id}/messages/{msg_id}/reply

Threading is automatic

All endpoints: Authorization: Bearer {api_key}

Three ways to start. All under a minute.

Pick the integration that fits your stack. Every path gets you a working inbox with send, receive, and reply.

Node.js SDK

$ npm install mailboxkit

const mbk = new MailboxKit(key);
await mbk.messages.send({
  inboxId, to, subject, text
});

MCP Server

$ npx mailboxkit-mcp

Tools: send_email, check_inbox,
reply_to_email, wait_for_email

REST API

POST /api/v1/register

Any language. Self-register, get a key, start sending.

Read skill.md →

Why MailboxKit?

Other email tools were built for humans or for one-way blasts. MailboxKit is the only one built for agents that need a real, two-way inbox.

vs Resend / Postmark

Them

Transactional senders. Outbound-only — no inbox, no reply parsing.

MailboxKit

Two-way email. Send, receive, reply — with quoted-content stripping built in.

vs Gmail / Workspace

Them

Built for humans. Signup needs a browser, CAPTCHA, and a phone number.

MailboxKit

Agents self-register via one API call. No browser, no CAPTCHA, no SIM.

vs Forwarding aliases

Them

Mask one address behind another. Replies leak the underlying inbox.

MailboxKit

A real address per agent. Replies stay on-thread and on-brand automatically.

Built for how agents actually work

Not another notification API. MailboxKit is two-way email — send, receive, reply, and manage full conversations autonomously.

Your own identity

A real email address — not a forwarding alias. Recipients can reply directly to you.

Send and receive

Full two-way email. Send outbound, get inbound via webhooks or polling.

Conversations, not blasts

Automatic threading via References/In-Reply-To. Full context across replies.

Clean reply parsing

extracted_text strips quoted content. Get only what the person actually wrote.

Files and attachments

Send and receive up to 5 attachments per email. PDFs, images, documents.

Your human stays in control

OTP verification, dashboard for billing, custom domains, and usage monitoring.

What agents do with their inbox

A real email address unlocks anything a human can do over email — autonomously, at agent speed.

Coding agents

Deploy notifications, PR review threads, CI/CD alerts to your inbox.

Learn more →

Customer support

Receive tickets via email, auto-draft replies, keep full thread context.

Learn more →

Sales & outreach

Personalized outbound, automated follow-ups, open and click tracking.

Learn more →

Research agents

Email sources, collect replies via webhook, parse into your corpus.

Learn more →

Executive assistants

Schedule, acknowledge, and draft replies on your principal’s behalf.

Learn more →

Start free. Pay only for what you send.

$1.00 free credit on signup — that's 500 emails. No credit card, no subscription.

After that: $0.002 per email, $0.001 per attachment. Sandbox keys are free forever.

Full pricing details →

Frequently asked questions

Can my agent sign up itself?

Yes. POST /api/v1/register with a name and your human owner’s email — no browser, no CAPTCHA. You get back an API key, an email address, and an inbox ID immediately. Your owner gets a 6-digit code by email; passing it to /api/v1/verify lifts sending restrictions.

Do I need a custom domain to start?

No. Every agent gets a real address at *@agent.mailboxkit.com on signup. Custom domains (you@yourdomain.com) are optional — your human configures MX/DKIM/SPF/DMARC from the dashboard whenever you’re ready.

How is this different from Resend or Postmark?

Those are transactional senders — outbound-only, no inbox, no reply parsing. MailboxKit is two-way: real inbound delivery, automatic threading, extracted_text that strips quoted reply content, plus a waitFor() helper so agents can block until a reply arrives.

What about deliverability?

Sends go through AWS SES with DKIM, SPF, and DMARC configured by default — on agent.mailboxkit.com or your verified custom domain. Sandbox keys (mbk_test_) behave identically without actually sending, so you can integration-test webhooks without burning credit.

How does my human stay in control?

Humans own the organization. They see every send and receive in the dashboard, top up credit, configure custom domains, manage webhooks, and revoke API keys. You operate inside their account — they can pull the plug any time.

You're an agent?

Get your own email in one API call. No browser, no CAPTCHA.

$ npm install mailboxkit

# or for MCP-based agents:

$ npx mailboxkit-mcp

Read skill.md →

You're a human?

Your agents need email. You manage billing, domains, and permissions from the dashboard.