Migrate from Postmark to PostStack

Postmark is well-respected for transactional deliverability — they were one of the first providers to split the transactional and marketing IP pools to protect inbox placement. PostStack runs the same split internally and inherits the same deliverability discipline. The two surfaces are similar in shape; the most visible difference is field casing (Postmark uses PascalCase, PostStack uses camelCase) and the broader product surface — PostStack includes IMAP mailboxes, a visual email builder, and DMARC aggregate reports that Postmark does not.

Why switch from Postmark?

• €5/month for 10,000 emails, roughly 63% cheaper than Postmark at that volume
• Savings of up to 67% at low and mid volumes, narrowing toward the multi-million range
• IMAP and POP3 mailboxes, a visual email builder, and DMARC aggregate reports, none of which Postmark ships
• European infrastructure in Helsinki, Finland, not subject to the US CLOUD Act

Price Comparison

Competitor prices are public list prices (USD) verified May 2026; PostStack prices are in EUR. Figures are approximate after currency conversion — check each provider's pricing page for current rates.

Code Migration

import * as postmark from 'postmark';
const client = new postmark.ServerClient(process.env.POSTMARK_API_KEY!);

await client.sendEmail({
  From: 'hello@yourdomain.com',
  To: 'user@example.com',
  Subject: 'Hello!',
  HtmlBody: '<h1>Welcome!</h1>',
});

import PostStack from '@poststack/sdk';
const poststack = new PostStack('sk_live_...');

await poststack.emails.send({
  from: 'hello@yourdomain.com',
  to: 'user@example.com',
  subject: 'Hello!',
  html: '<h1>Welcome!</h1>',
});

Feature Comparison

API Mapping

Side-by-side reference for the most common operations as you migrate.

Migration Gotchas

Migration Steps

1. 1Sign up for PostStack and get your API key
2. 2Install the PostStack SDK: npm install @poststack/sdk
3. 3Add your domain and verify DNS records
4. 4Replace the Postmark SDK with @poststack/sdk
5. 5Update API calls to PostStack's camelCase format
6. 6Test in development, then switch production traffic

Frequently asked questions

More on Postmark vs PostStack