Migrate from Postmark
to Posthawk
Move from Postmark to Posthawk and cut your email costs by up to 10x while maintaining the same delivery quality through AWS SES.
Migration steps
Export templates and data
Download your Postmark templates via their API. Export your suppression list and server settings for reference during setup.
Tip: Use GET /templates?count=100 to export all templates, then convert to Posthawk format.
Deploy Posthawk
Set up Posthawk with Docker Compose. The Postmark concept of "servers" maps to Posthawk "workspaces" — create one per environment.
Configure your domain
Add your domain in Posthawk and update DNS records. Posthawk uses BYODKIM (your own key pair) instead of Postmark's managed DKIM.
Migrate API calls
Replace Postmark API endpoints with Posthawk equivalents. The request/response shapes are similar with minor field name changes.
Validate delivery
Send test emails to major providers (Gmail, Outlook, Yahoo). Compare delivery rates and timing against your Postmark baseline.
Tip: AWS SES has excellent deliverability — most users see identical or better rates vs Postmark.
Cut over
Switch DNS and update production environment variables. Monitor the Posthawk dashboard for delivery metrics over the first 48 hours.
API mapping
Before & after
const postmark = require('postmark');
const client = new postmark.ServerClient(process.env.POSTMARK_API_KEY);
await client.sendEmail({
From: 'hello@yourapp.com',
To: 'user@example.com',
Subject: 'Welcome!',
HtmlBody: '<h1>Hello!</h1>',
MessageStream: 'outbound',
});const response = await fetch('https://api.posthawk.dev/api/v1/email/send', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'x-api-key': process.env.POSTHAWK_API_KEY,
},
body: JSON.stringify({
to: 'user@example.com',
from: 'hello@yourapp.com',
subject: 'Welcome!',
html: '<h1>Hello!</h1>',
}),
});Common gotchas
Message Streams → Workspaces
Postmark uses "Message Streams" to separate transactional and broadcast. In Posthawk, use separate workspaces or API keys for this.
Field names are lowercase
Postmark uses PascalCase (From, To, Subject). Posthawk uses camelCase (from, to, subject). Update your request bodies.
Inbound webhook format differs
Postmark inbound webhooks have a different JSON structure. Update your handler to parse Posthawk's inbound email format.
No built-in click/open tracking
Postmark includes optional click and open tracking. Posthawk focuses on transactional delivery — use a dedicated analytics tool if you need engagement tracking.
More migration guides
Migrate from Resend
Switch from Resend to Posthawk while keeping the modern developer experience you love.
Read guideReady to migrate?
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