API v1.0 — Live

Email infrastructure
for developers

The relay, inbound routing, and analytics engine your app plugs into. Build MailChimp-style or Gmail-style products on Sleeng Mail — without touching MX records or SMTP servers.

Read the docs → Create account
terminal
$ curl -X POST https://api.sleengmail.com/v1/send \
-H "X-API-Key: ep_live_••••••••••" \
-H "Content-Type: application/json" \
-d '{ "from": "hello@yourdomain.com",
"to": ["user@example.com"],
"subject": "Welcome aboard",
"html": "<h1>Hello!</h1>" }'
# response
{
"message_id": "msg_01j9x...",
"status": "queued"
}

Comparable to

SendGrid Amazon SES Postmark Mailgun

Platform capabilities

Everything your app needs
to send and receive email

One platform for outbound delivery, inbound routing, event tracking, and deliverability management.

📤

SMTP Relay

Point your app at our SMTP endpoint on port 587. We authenticate, DKIM-sign, and deliver to every major provider.

📥

Inbound Routing

Receive email for your customer domains. We parse, spam-filter, and POST to your webhook in real time.

📊

Event Pipeline

Every delivery, bounce, open, click, and complaint becomes a structured event — via webhooks and the analytics API.

🔑

Multi-Tenant API

Full REST API for domain management, API keys, webhooks, suppression lists, and per-customer analytics.

🛡️

Deliverability

DKIM per customer domain, IP pools, automatic bounce and complaint handling, and ISP feedback loop registration.

🔗

Signed Webhooks

Real-time delivery to your endpoint with HMAC-SHA256 signing. Automatic retries with exponential backoff.

< 1s
Avg. delivery time
99.9%
Platform uptime
TLS
All connections encrypted
REST
Simple JSON API

Getting started

Up and running
in minutes

01

Create an account

Register your organization via the API. You get a JWT token immediately — no approval process.

02

Add a sending domain

Submit your domain. We generate SPF, DKIM, and DMARC DNS records. Publish them and we auto-verify.

03

Generate an API key

Create a scoped API key. Use it in the X-API-Key header on the send endpoint.

04

Send your first email

POST to /v1/send with from, recipients, subject, and HTML. Delivery is async — a message_id comes back immediately.

05

Monitor delivery events

Register a webhook to receive real-time delivery, bounce, open, and click events as they happen.

Ready to start sending?

Your app deserves
reliable email delivery

Read the API reference and make your first send in under five minutes.

View API docs → Create account