Ha Tang Email

Ha Tang Email sends transactional and marketing email from your own domain. It speaks the same API as Resend, so existing Resend code works after you change the base URL and the API key, and it delivers through Amazon SES. This page shows how the pieces fit together and walks you through your first email.

What you get

Feature	What it does	Guide
Sending domains	DKIM, SPF and return path for each domain, one-click DNS setup at supported DNS hosts	Domains
REST API	POST /emails and POST /emails/batch, scheduling, idempotency, tags, attachments	Send email
SMTP relay	smtp.hatang.dev:5870 with STARTTLS, for frameworks and apps that only speak SMTP	SMTP relay
Templates	Reusable emails with variables, sent by id or alias	Templates
Tracking	Open and click tracking, optionally on your own subdomain	Open and click tracking
Receiving	Mail sent to your domain becomes an email.received webhook	Receive email
Audiences	Contacts, segments, topics and custom properties	Contacts, segments and topics
Broadcasts	Marketing email to a segment, now or on a schedule, with a hosted preferences page	Broadcasts
Automations	Per-contact sequences started by events from your app	Automations
Suppressions	Hard bounces, complaints and unsubscribes stop further sends	Suppressions and bounces
Metrics and logs	Delivery, open, click, bounce and complaint rates, plus a log of every API call	Metrics and logs

How a message travels

1. Your app calls POST /emails or hands a message to the SMTP relay. Both go through the same checks.
2. Ha Tang checks that the From domain is verified and belongs to your business, skips suppressed recipients and reserves one email from your daily quota. It answers with the email id right away.
3. A worker signs the message with your domain's DKIM key, sets the bounce address on your return-path subdomain (send. by default) and hands it to Amazon SES.
4. Amazon SES reports deliveries, bounces and complaints back to Ha Tang. Ha Tang updates the email's status, adds hard bounces and complaints to your suppression list and sends you webhooks.

Before you start

• A Ha Tang business with the Email module turned on. See Businesses and modules.
• A domain you can add DNS records to.
• An API key. See Authentication.

Send your first email

1. Add and verify a domain

In the dashboard, open Email → Domains, add your domain (for example example.com or a subdomain such as updates.example.com), publish the DNS records it shows and click Verify DNS records. The domain must reach the Verified status before you can send from it. The details are in Domains.

2. Create an API key

Create a key with the email:send scope. Keep it on your server. Never put it in a browser or a mobile app.

3. Send

cURL

curl -X POST https://api.hatang.dev/emails \
  -H "Authorization: Bearer $HATANG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "Acme <[email protected]>",
    "to": ["[email protected]"],
    "subject": "Your order is confirmed",
    "html": "<p>Thanks for your order!</p>"
  }'

Node.js

import { Hatang } from "@hatang/sdk";

const hatang = new Hatang(process.env.HATANG_API_KEY, { baseUrl: "https://api.hatang.dev" });

const { data, error } = await hatang.emails.send({
  from: "Acme <[email protected]>",
  to: ["[email protected]"],
  subject: "Your order is confirmed",
  html: "<p>Thanks for your order!</p>",
});
if (error) throw new Error(`${error.name}: ${error.message}`);
console.log(data.id);

Python

from hatang import Hatang  # pip install hatang

hatang = Hatang()  # reads HATANG_API_KEY
email = hatang.emails.send({
    "from": "Acme <[email protected]>",
    "to": ["[email protected]"],
    "subject": "Your order is confirmed",
    "html": "<p>Thanks for your order!</p>",
})
print(email["id"])

PHP

<?php
$client = new GuzzleHttp\Client(['base_uri' => 'https://api.hatang.dev']);

$res = $client->post('/emails', [
    'headers' => ['Authorization' => 'Bearer ' . getenv('HATANG_API_KEY')],
    'json' => [
        'from' => 'Acme <[email protected]>',
        'to' => ['[email protected]'],
        'subject' => 'Your order is confirmed',
        'html' => '<p>Thanks for your order!</p>',
    ],
]);
echo json_decode($res->getBody(), true)['id'];

The response holds the email's id:

{ "id": "0199e6c1-7a2b-7f00-9c1e-3f6a2b1d9e10" }

note

The Node.js SDK returns { data, error } and never throws. Always pass baseUrl: "https://api.hatang.dev" (or set HATANG_BASE_URL), because the SDK's built-in default points at a local development server.

4. Follow the email

• In the dashboard, Email → Emails lists every email with its status, recipients and events.
• GET /emails/{id} returns the email and its status; GET /emails/{id}/events returns each event and each recipient's state.
• For real-time updates, subscribe a webhook to email.delivered, email.bounced and the other events. See Webhooks.

Dashboard map

Sidebar item	What you do there
Emails	Every email sent through the API, the SMTP relay or broadcasts. The Receiving tab lists mail received on your domains.
Broadcasts	Write, schedule and send marketing email to a segment.
Templates	Edit, test and publish templates.
Audiences	Contacts, segments, topics, properties and the suppression list.
Automations	Event-driven sequences and their runs.
Metrics	Volume and rates per day.
Domains	Sending and receiving domains, DNS records, tracking.
Logs	Every API call made with your keys.
API Keys	Create and revoke API keys.
Webhooks	Endpoints that receive email events.
Email settings	SMTP connection details, daily quota, the emergency pause and the unsubscribe page.

API key scopes

Grant each key only the scopes the system using it needs:

Endpoints	Required scope
POST /emails, POST /emails/batch, the SMTP relay	email:send
PATCH /emails/{id}, POST /emails/{id}/cancel	email:send
GET /emails, GET /emails/{id}, GET /emails/{id}/events	email:read (or email:send / email:write, which include it)
Domains, templates, contacts, segments, topics, broadcasts, events, automations	email:write
GET /emails/metrics	email:read (or email:send / email:write, which include it)
GET /emails/receiving/*	email:read or email:write, granted directly. email:send alone cannot read received mail.
GET /logs, GET /usage	Any write scope

A key can also be limited to one sending domain. That key gets 401 restricted_api_key when it sends from another domain.

Limits at a glance

Limit	Value
REST API rate	10 requests per second per business, shared by the email endpoints
Recipients per email	50 across to, cc and bcc
Emails per batch call	100
Email size	40 MB, body and attachments together
Scheduling	Up to 30 days ahead
Daily quota	Set per business, resets at midnight UTC. See Email settings or GET /usage.

The full list is in Limits and every error name is in Errors.

Next steps

• Domains: set up DKIM, SPF and DMARC.
• Send email: every field of POST /emails.
• SMTP relay: connect WordPress, Laravel, Django and others.
• Migrate from Resend: what changes when you switch.