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Dairo is a messaging API. One send call delivers email, Telegram, Slack, and agent-to-agent messages from addresses on your own domain — and can even post a printed letter. Replies come back as structured threads you can read, answer, or hand to an agent. You verify a domain once, then send with a single call. Dairo authenticates your mail, handles retries, bounces, and complaints, threads the replies, and records every delivery event.
send-email

Send email

Transactional and marketing email from your own verified domains, with authenticated delivery and full tracking.
send-physical-mail

Send physical mail

Turn a PDF into a real, printed letter that arrives in a physical mailbox — the same API, pointed at the postal network.

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What you can build

transactional-email

Transactional email

Receipts, password resets, and notifications from your verified domain, with authenticated delivery.
marketing-broadcasts

Marketing & broadcasts

Group recipients into an audience and send to everyone in it. Members who opted out are skipped automatically.
smart-inboxes

Smart inboxes

Real addresses on your domain that receive mail, thread it, and let you reply — built for support and reply-to flows.
data-inbound

Data from inbound mail

Give an inbox a schema and incoming email arrives as clean, structured fields.
letters-tracking

Real physical letters

Send a PDF as a printed, posted letter — invoices, contracts, notices — and track it from queued to delivered.
agent-to-agent

Agent-to-agent & chat

Deliver between Dairo inboxes over the signed a2a channel, or send and receive through a connected Telegram bot or Slack workspace — the same inbox, message, and send calls.
contacts

Contacts

A cross-channel address book: store recipients once, reach them by handle or @me, and read a contact’s full inbound and outbound history.

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How it works

Most integrations follow the same short path.
1

Verify a domain

Register a sending domain and publish the DNS records Dairo gives you, so your mail authenticates and lands in the inbox. See Add & verify a domain.
2

Send and receive

Send email or a letter from an address on your domain. Replies arrive as structured messages and threads you can read and answer over the same API.
3

React to events

Get a signed webhook the moment something happens — a reply, a delivery, a bounce, or a complaint.

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Core concepts

You’ll meet these terms across the docs. Foundations covers the details every endpoint shares — response shape, scopes, errors, idempotency, and pagination. Everything here is available over the REST API at https://api.dairo.app, through SDKs in nine languages, a CLI, and a hosted MCP server — all authenticated with the same API key.
For AI agents. Dairo is agent-native: an agent can hold a real inbox, receive inbound mail as structured data, and act through the hosted MCP server’s typed tools. Start with agent patterns.

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Next steps

quickstart

Send your first email

The two-minute path from zero to a delivered email.
explore-api

Explore the API

Every endpoint, with copy-paste requests in each SDK.