SendMailOS API
Powerful email infrastructure for developers. Send transactional and marketing emails at scale with our REST API.
Base URL
All API requests should be made to the following base URL:
Authentication
Authenticate your API requests by including your API key in the Authorization header:
Authorization: Bearer sk_live_your_api_keyKeep your API key secure
Never expose your API key in client-side code. Use environment variables and server-side requests.
Send Your First Email
Get started with a simple API call to send a transactional email.
curl -X POST https://sendmailos.com/api/v1/send \
-H "Authorization: Bearer sk_live_..." \
-H "Content-Type: application/json" \
-d '{
"to": "[email protected]",
"from_name": "Acme Corp",
"from_email": "[email protected]",
"subject": "Welcome to Acme!",
"html": "<h1>Welcome!</h1><p>Thanks for signing up.</p>"
}'Response
{
"success": true,
"message_id": "msg_1234567890abcdef",
"status": "queued"
}Why SendMailOS?
Everything you need to build reliable email infrastructure.
High Performance
Send millions of emails with sub-second API latency and 99.9% uptime.
Enterprise Security
SOC 2 compliant with DKIM, SPF, and DMARC authentication built-in.
Global Delivery
Distributed infrastructure ensures fast delivery worldwide.
Developer First
Clean REST API, official SDKs, and comprehensive documentation.
Real-time Webhooks
Get instant notifications for bounces, opens, clicks, and more.
Agency Workspaces
Manage multiple clients with isolated data, scoped API keys, and per-client analytics.
Ready to get started?
Follow our quickstart guide to send your first email in under 5 minutes.