PostStack vs SendGrid: Modern Email API vs the Legacy Incumbent

SendGrid (now part of Twilio) has been the default transactional email API since 2009. It's still everywhere, but the v3 API shows its age and the pricing model is full of fine print. PostStack is the modern, EU-hosted alternative. Here's how they compare.

Pricing

SendGrid's free tier is 100 emails/day — a daily cap, not a monthly one — which trips up teams that have bursty volume. The first paid tier is $19.95/month regardless of whether you need 10,000 or 50,000 emails. PostStack prices per actual volume tier.

3,000/month: SendGrid $0 (but capped at 100/day) · PostStack €0
10,000/month: SendGrid $19.95 · PostStack €5 — 75% cheaper
50,000/month: SendGrid $19.95 · PostStack €15 — 25% cheaper
100,000/month: SendGrid $89.95 · PostStack €65 — 28% cheaper
500,000/month: SendGrid $449 · PostStack €325 — 28% cheaper

SendGrid also gates dedicated IPs, advanced stats, and single-sign-on behind upgrade add-ons. PostStack includes dedicated IPs on the Scale plan and ships SSO without a separate enterprise contract.

API design

SendGrid's v3 API uses JSON keys like personalizations and dynamic_template_data, inherited from an older SMTP-to-JSON era. It works, but it feels like 2015. PostStack's API takes the cleaner { from, to, subject, html } shape that Resend popularised.

// SendGrid v3
await sgMail.send({
  to: 'user@example.com',
  from: 'hello@yourdomain.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>',
});

Features PostStack ships that SendGrid doesn't

IMAP/POP3 mailboxes — PostStack runs Dovecot mailboxes for your verified domains. SendGrid is send-only.
DMARC aggregate report parsing — SendGrid leaves DMARC reports in your inbox as XML attachments. PostStack parses and charts them.
Visual email builder in the dashboard — SendGrid's builder is part of the separate Marketing product, not the base email API.
Workflow automation on transactional plans — SendGrid's automation requires the Marketing Campaigns product.
EU data residency — SendGrid is US-only infrastructure.

Where SendGrid is genuinely better

SendGrid's scale is real — they process billions of emails and have feedback loops with virtually every ISP on earth. If you're sending tens of millions of emails per month to a global audience, SendGrid's infrastructure depth is hard to match. They also have a bigger ecosystem of third-party integrations and a longer track record with legacy platforms (Salesforce, HubSpot, older CMSes).

Deliverability

Both services handle SPF, DKIM, and DMARC setup. SendGrid has a longer reputation history and separate IP pools, while PostStack uses Rspamd pre-flight scoring to catch spam-triggering content before it leaves your account. For most teams at under 1M emails/month the difference is negligible; both deliver.

When to pick each

Pick SendGrid if you already use Twilio for SMS, you're on a legacy platform that only supports SendGrid out of the box, or your volume is high enough to justify an enterprise conversation.

Pick PostStack if you want a modern API, EU-hosted infrastructure, predictable pricing without per-feature add-ons, and built-in features like IMAP mailboxes and DMARC reporting.

Migrating from SendGrid

The SendGrid migration guide walks through replacing @sendgrid/mail with @poststack/sdk. Most teams complete it in under an hour. Start on the free plan to try both in parallel.