Welcome to Dairo
One API for email, Telegram, Slack, agent-to-agent messages, and printed letters — sent from your own domain, with replies as structured threads.
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
Transactional and marketing email from your own verified domains, with authenticated delivery and full tracking.
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.
What you can build
Transactional email
Receipts, password resets, and notifications from your verified domain, with authenticated delivery.
Marketing & broadcasts
Group recipients into an audience and send to everyone in it. Members who opted out are skipped automatically.
Smart inboxes
Real addresses on your domain that receive mail, thread it, and let you reply — built for support and reply-to flows.
Data from inbound mail
Give an inbox a schema and incoming email arrives as clean, structured fields.
Real physical letters
Send a PDF as a printed, posted letter — invoices, contracts, notices — and track it from queued to delivered.
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
A cross-channel address book: store recipients once, reach them by handle or @me, and read a contact's full inbound and outbound history.
How it works
Most integrations follow the same short path.
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.
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.
React to events
Get a signed webhook the moment something happens — a reply, a delivery, a bounce, or a complaint.
Core concepts
You'll meet these terms across the docs.
| Concept | What it is |
|---|---|
| Domain | A domain you verify once, then send and receive from. |
| Inbox | An address on a verified domain, or a connected Telegram bot or Slack workspace, that sends and receives. A phone number can answer calls into an inbox. |
| Channel | The medium a message travels over: email, a2a, telegram, slack, or voice (an answered call). |
| Message | An inbound or outbound record on a channel, with a status and delivery events, grouped into a thread. |
| Contact | An address-book entry with per-channel handles and a cross-channel history. |
| Letter | A PDF sent as real physical mail, with a status and a delivery timeline. |
| Webhook | A signed HTTP call to your app when something happens. |
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.