Email for LangChain Agents

Give every LangChain agent its own inbox. Create inboxes via API, deliver inbound emails as structured JSON, and handle full conversation threads — no SMTP config, no deliverability headaches.

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How OpenMail works with LangChain

01

Create an inbox per agent

One API call provisions a live inbox on your domain and returns the address immediately. This runs in your provisioning code with your account key — the agent never sees that key.

Node.js
const response = await fetch("https://api.openmail.sh/v1/inboxes", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.OPENMAIL_ACCOUNT_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({ mailboxName: userId }),
});
const inbox = await response.json();
// inbox.id      → "inb_8f3a1b2c"
// inbox.address → "agent@yourdomain.com"
02

Mint a key scoped to that inbox

Give each agent a key that reaches only its own inbox. It can read and send from that one inbox and nothing else — so a prompt injection in one agent's mail can't reach another agent's inbox. The token is returned once; store it with the agent's config.

Node.js
const res = await fetch(
  `https://api.openmail.sh/v1/inboxes/${inbox.id}/api-keys`,
  {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.OPENMAIL_ACCOUNT_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ name: `agent:${userId}` }),
  },
);
const { token } = await res.json();
// token → "om_..."  shown once, never retrievable again
03

Pass credentials to your agent

Three environment variables. All three are unique per agent — the key is the inbox-scoped one you just minted, not your account key.

env
OPENMAIL_API_KEY=om_...          # scoped to this inbox only
OPENMAIL_INBOX_ID=inb_8f3a1b2c
OPENMAIL_ADDRESS=agent@yourdomain.com
04

Send and reply from the agent

Your LangChain agent sends email via the API. Save the threadId to reply in the same thread later.

Python
import os, requests

def send_email(to, subject, body, thread_id=None):
    payload = {"to": to, "subject": subject, "body": body}
    if thread_id:
        payload["threadId"] = thread_id
    response = requests.post(
        f"https://api.openmail.sh/v1/inboxes/{os.environ['OPENMAIL_INBOX_ID']}/send",
        headers={"Authorization": f"Bearer {os.environ['OPENMAIL_API_KEY']}"},
        json=payload,
    )
    return response.json()
05

Receive inbound emails as structured events

Connect via WebSocket — no public URL needed. When an email arrives, OpenMail fires an event with the parsed message body, thread context, and any extracted attachments. An inbox-scoped key only ever streams its own inbox, so each agent sees just its own mail.

Python
import asyncio, json, os, websockets

async def listen():
    uri = "wss://api.openmail.sh/v1/ws"
    headers = {"Authorization": f"Bearer {os.environ['OPENMAIL_API_KEY']}"}
    async for ws in websockets.connect(uri, extra_headers=headers):
        try:
            await ws.send(json.dumps({"type": "subscribe"}))
            async for raw in ws:
                event = json.loads(raw)
                if event.get("event") == "message.received":
                    # Scoped key → only this agent's inbox arrives here
                    message = event["message"]
                    # Pass to your LangChain agent
        except websockets.ConnectionClosed:
            continue

asyncio.run(listen())

What your LangChain agent can do with email

Send emails autonomously from a branded address on your domain

Receive replies in real time via WebSocket — no polling

Read full thread history as structured JSON for context

Parse PDF, CSV, and DOCX attachments automatically

Handle OTP codes and verification links for autonomous signup flows

What's included

Dedicated inbox per agent

Each LangChain agent gets its own address on your domain — no shared inboxes, no filtering logic.

Real-time inbound delivery

WebSocket events delivered in under 500ms. Your agent receives email the moment it arrives.

Full thread history as structured JSON

Pull complete conversation context via the history endpoint and feed it directly into your agent's context window.

Attachment parsing

PDF, CSV, and DOCX files automatically extracted to plain text. Your agent gets the content without handling MIME types.

Managed deliverability

SPF, DKIM, and DMARC configured automatically on provisioning. Primary inbox from day one.

Works with any LangChain version

REST API, no SDK required. Any LangChain agent that can make HTTP requests works with OpenMail.

Frequently asked questions

Every LangChain agent deserves its own inbox.

Start For Free →Read the integration docs →