Master Postmark with our step-by-step tutorial, detailed feature walkthrough, and expert tips.
Create Postmark account and verify sender domain Set up DKIM authentication for deliverability Create templates for common agent email scenarios Integrate simple API into agent communication workflows Configure webhooks for delivery tracking and user engagement
💡 Quick Start: Follow these 1 steps in order to get up and running with Postmark quickly.
Explore the key features that make Postmark powerful for messaging & communication workflows.
All sending occurs on infrastructure exclusively used for transactional email. No marketing senders share IP addresses, maintaining pristine sender reputation and consistent inbox placement.
Sending security alerts and password reset emails from an AI agent where landing in spam would be a critical failure.
Average email delivery time under 10 seconds from API call to inbox arrival. Postmark prioritizes delivery speed for transactional messages where timing matters.
An agent that sends two-factor authentication codes where delivery delay directly impacts user experience.
Create separate sending streams for different transactional email types with independent tracking, analytics, and reputation monitoring. Each stream can have its own templates and webhooks.
Separating agent notification emails from receipt emails into different streams to independently monitor deliverability for each type.
Receives incoming emails and forwards them as structured JSON (headers, text body, HTML body, attachments) to your webhook endpoint. Supports reply tracking that links inbound emails to previously sent messages.
Building an email-based agent interface where users reply to agent-sent emails and the replies are parsed and processed by the AI.
Server-managed email templates with Mustachio variable substitution and shared layouts. Templates are versioned and can be managed via API. Layout templates provide consistent branding across all email types.
An agent that sends multiple types of emails (alerts, reports, confirmations) using templates that all share the same branded layout.
Real-time webhooks for delivery, bounce, open, click, and spam complaint events. Dashboard shows delivery rates, open rates, and bounce classifications with 45-day retention.
Monitoring agent email performance to detect deliverability issues before they impact users, with automated alerting on bounce rate spikes.
By design. Marketing emails receive spam complaints, which degrade IP reputation. Postmark keeps its infrastructure transactional-only to maintain the highest possible deliverability for your important emails. Use a separate service (SendGrid, Mailchimp) for marketing.
Both focus on developer experience. Postmark has a longer track record, proven deliverability metrics, and dedicated transactional infrastructure. Resend has a more modern API design, React email template support, and is growing fast. For proven reliability, Postmark. For cutting-edge developer experience, Resend.
Postmark monitors sending patterns and will flag or suspend accounts that send bulk marketing content. Their terms of service explicitly prohibit marketing email. They're serious about this — it's how they maintain deliverability for all customers.
SES is roughly 10x cheaper per email. Postmark provides better deliverability, faster delivery, a much cleaner API, and real-time support. For critical transactional emails where inbox placement and speed matter, Postmark's premium is justified. For high-volume notifications where some spam folder delivery is acceptable, SES is more cost-effective.
Now that you know how to use Postmark, it's time to put this knowledge into practice.
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Tutorial updated March 2026