Postmark: Fast, Reliable Email Delivery Service | SMTP | API

# Postmark > Postmark is a reliable transactional email service that helps developers deliver and track application emails. It provides REST APIs, SMTP support, webhooks, and comprehensive email templates to replace traditional SMTP with a scalable, developer-friendly solution. ## Quick Start To use Postmark for sending emails in your application: 1. Create a Postmark account and verify your sending domain or email address 2. Get your Server API Token from your Postmark server settings 3. Use the REST API or SMTP to send emails 4. Maximum email size is 10 MB (including attachments) 5. Maximum 50 recipients per email (To, CC, BCC combined) ### Authentication All API requests require authentication using the `X-Postmark-Server-Token` header with your Server API Token: ``` X-Postmark-Server-Token: your-server-token-here ``` For testing without actually sending emails, use `POSTMARK_API_TEST` as your token. ## API Reference - [Send a single email](https://postmarkapp.com/developer/api/email-api#send-a-single-email): POST to `/email` endpoint - [Send batch emails](https://postmarkapp.com/developer/api/email-api#send-batch-emails): POST to `/email/batch` endpoint - [Send with templates](https://postmarkapp.com/developer/api/templates-api#send-email-with-template): POST to `/email/withTemplate` endpoint - [Send batch with templates](https://postmarkapp.com/developer/api/templates-api#send-batch-with-templates): POST to `/email/batchWithTemplates` endpoint - [Send bulk emails](https://postmarkapp.com/developer/api/bulk-email): POST to `/email/bulk` endpoint for broadcast streams - [Template management](https://postmarkapp.com/developer/api/templates-api): Create, edit, list templates via API - [Bounce API](https://postmarkapp.com/developer/api/bounce-api): Manage bounced emails and reactivate addresses - [Message tracking](https://postmarkapp.com/developer/api/messages-api): Search and retrieve message details - [Stats API](https://postmarkapp.com/developer/api/