PostStack vs Resend: Which Email API Should You Choose?

Resend is the benchmark every modern transactional API gets compared to — including PostStack, which I run. The two products look similar by design: PostStack deliberately copied Resend's API shape and webhook event vocabulary so migrating between them is essentially a rename. Where they diverge is pricing, infrastructure geography, and how much sits in the base plan vs an upgrade tier. Here's the comparison written by someone who built one of them.

Pricing at real volume

Resend's free tier is generous (3,000/month with a 100/day cap), but the first paid tier starts at $20. The moment you cross 3,000 sends, you go to $20. PostStack's first paid tier is €5.

Monthly cost at common volumes:

3,000 emails: Resend $0 · PostStack €0
10,000 emails: Resend $20 (Pro) · PostStack €5 — ~72% cheaper
50,000 emails: Resend $20 (Pro) · PostStack €15 — ~19% cheaper
100,000 emails: Resend $35 (Pro) or $90 (Scale) · PostStack €30 — ~7% cheaper
500,000 emails: Resend $350 (Scale) · PostStack €130 — ~60% cheaper

Resend's pricing was simpler last year — Pro was a flat $20 up to 50K and then straight to Scale at $90 for 100K. They've since added a $35/100K Pro option, which narrows the gap at that volume specifically.

Where Resend is genuinely better

Resend's React Email integration is first-party and well-maintained. If your entire email design system is built on React components, that workflow is smoother than any templating system, including ours. Resend also has a larger community, more third-party tutorial content, and a marketing budget that PostStack can't match.

Where PostStack is better

IMAP/POP3 mailboxes — real Dovecot mailboxes for support@yourdomain.com and team mailboxes. Resend doesn't do mailboxes; you'd pair it with Migadu or Fastmail.
Visual email builder — drag-and-drop block editor in the dashboard. Resend leaves you to build your own.
Parsed DMARC aggregate reports — incoming XML reports get parsed and charted automatically. Resend doesn't surface them.
Workflow automation — multi-step sequences with delays and branches. Resend's audience features stop at one-shot broadcasts.
Embeddable signup forms — drop-in form widget that writes straight into your contact list.
EU data residency — Helsinki, Finland infrastructure, run by a Danish company. Resend is US-headquartered with US infrastructure.
Dedicated IPs as a €25/mo add-on from Pro up, not gated behind "contact sales".

Developer experience

The two SDKs are deliberately near-identical. A send call:

typescript

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

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

Both ship TypeScript SDKs with the same event vocabulary on webhooks (delivered, bounced, opened, clicked, complained, unsubscribed). Migration in practice is a find-and-replace plus an env var rotation.

When to pick each

Pick Resend if you're all-in on React Email, you're a US team without an EU residency requirement, and the extra ~$15/month at 10,000 sends isn't worth thinking about.

Pick PostStack if you want the same clean API at a lower price band, EU data residency, real mailboxes, and DMARC parsing without an enterprise contract.

Migrating from Resend

The SDK is a drop-in. See the Resend migration guide for the exact steps, or start on the free plan to run PostStack alongside Resend before switching.