MailKite
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AI agent infrastructure

Email inbox for AI agents

Give your agent its own inbox. Receive, parse, and send email via MCP or API. Unlimited domains, free — no credit card, no mail server.

Connect your agent
Connect to the MailKite MCP server (Streamable HTTP) at
https://mcp.mailkite.dev/mcp and authenticate in the browser when prompted.
Then use the mailkite_* tools to send, read inbound, and reply to email.

Works with Claude, GPT, LangChain, CrewAI, or any MCP-compatible agent. Also available as a REST API for non-MCP agents.

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Switched from SendGrid, inbox placement went from ~92% to ~99% in two weeks.

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How it works

Receive → Parse → Act → Reply

Email arrives at your agent's domain. MailKite parses it into clean JSON and delivers it to your endpoint. Your agent processes it and replies with one API call. The full loop, no mail server required.

Inbound — receive email Receive
// POST https://your-agent.com/api/mailkite/webhook
{
  "from": "user@example.com",
  "to": "agent@my-agent.com",
  "subject": "Help me with my task",
  "text": "Can you check the status of order #1234?",
  "html": "<p>Can you check the status of order #1234?</p>",
  "attachments": []
}
Outbound — agent replies Send
// Agent processes → replies via MailKite
await mk.send({
  "to": "user@example.com",
  "subject": "Re: Help me with my task",
  "text": "Order #1234 is shipped. ETA: Thursday."
});

The full receive → process → reply loop. Your agent handles email like any other tool — no SMTP, no IMAP, no mail server.

Try it

One prompt. Your agent sends email.

Paste a prompt into your agent — it connects to MailKite and sends. Prefer the raw SDK? Toggle to the code tab.

Send an email
Send an email to user@example.com with subject "Hello from my agent" and body "Your agent just sent its first email."
Read the inbox
Check my MailKite inbox for new emails and show me the latest one.
Reply to a message
Reply to the email from user@example.com with subject "Help needed" — say "Order #1234 is shipped. ETA: Thursday."
Process inbound webhooks
When an email arrives at my MailKite webhook, read it, and reply with a helpful response based on what the sender asked.

Every prompt uses the same MCP server your agent connects to once. No per-action setup — just paste and go.

Why MailKite

Built for agent builders.

Email that works like a tool, not infrastructure. MCP-native, inbound-first, and zero mail servers to maintain.

MCP-native

MailKite ships as an MCP server. Connect it to Claude, GPT, or any MCP-compatible agent and email becomes a first-class tool — no custom glue code, no API wrappers.

Inbound arrives as clean JSON

Every email your agent receives is parsed into structured JSON — from, to, subject, text, HTML, attachments. Your agent reads it like any other tool output. No MIME parsing, no multipart decoding.

Unlimited domains, one key

Each agent gets its own domain and inbox. Add as many agents as you need — no per-domain charges, no per-agent tax. One API key manages everything.

Compare

What you stop building.

Agent builders comparing MailKite, rolling your own, and generic email APIs. Here's the gap.

MailKite Roll your own Generic email API
MCP server Built-in, zero config Build + maintain yourself Not available
Inbound as JSON Automatic, clean payload Parse MIME yourself Webhook with raw MIME
Agent reply loop One send call, threaded Build threading + state Send only, no threading
Domains Unlimited, free Pay per domain 1 (free tier)
Auth (SPF / DKIM / DMARC) Configured for you You publish and maintain You publish and maintain
Time to first inbox < 5 minutes Hours to days 30+ minutes
Credit card to start No N/A (infra costs) No (but limited)

Still deciding? Get your agent an inbox and try it yourself — no credit card.

Before you sign up

How does my agent receive email?

Point a domain at MailKite and add an inbound route to your agent's webhook endpoint. Every email arrives as structured JSON at your endpoint — from, subject, text, HTML, attachments. Your agent processes it like any other tool input.

What agents work with MailKite?

Any agent that supports MCP (Model Context Protocol) — Claude, GPT with tool use, LangChain agents, CrewAI, AutoGen, or custom agents. MailKite also works as a plain REST API for agents that don't use MCP.

Can my agent send email, not just receive?

Yes. Your agent calls POST /v1/send (or the SDK) to send email through MailKite. DKIM signing, deliverability tracking, and bounce handling are built in. Your agent can reply to emails, send notifications, or reach out to users.

Is it actually free?

Yes. Unlimited domains, no credit card, no daily send cap. You pay only when volume grows past the free threshold — and the beta rate is 50% off your first year for the first 1,000 customers.

What happens when I exceed the free tier?

Graceful overage — your agent's email never stops. You're notified when approaching limits and can upgrade with one click. No surprise cutoffs, no silent suspensions.

Give your agent an inbox today

Unlimited domains, free. MCP or API — your agent is sending in 5 minutes. No credit card, no mail server.

Free up to 3,000 emails/mo. $20/mo when you scale — no credit card.