Resend and Postmark both send transactional mail only, and both market themselves to developers. They are not the same product, though. Resend optimizes for developer experience: a small clean API, a React SDK, email components, and a product that gets out of your way. Postmark optimizes for deliverability: a strict reputation policy on its sending IPs, streams to isolate mail types, and a long track record of transactional mail arriving.
Postmark has been running transactional-only sending for years, and its IP reputation reflects that: no marketing campaigns, no shared bulk sending, strict content rules. When Postmark mail lands in spam, the cause is almost always on your side.
Resend is newer. It sends from shared infrastructure by default, and its IPs have a shorter history. For a small product sending modest volumes that is usually fine, but you are taking on more provider-side risk than with Postmark. Resend also offers dedicated IPs on higher tiers if you need isolation.
Resend is the better fit when you are building a new product and want the fastest path from code to sent email: a clean REST API, a React SDK, and email components you can drop into a UI. The documentation is short and the defaults are sane.
Postmark is the better fit when the mail itself is the product: order confirmations, account alerts, payment notices. Streams keep your mail types on separate reputations, and the dashboard surfaces problems early.
Resend prices by monthly volume with a free tier. Postmark prices per 10,000 emails with no free tier. Resend is cheaper at low and mid volume; Postmark costs more and buys the reputation model. Check current pricing before you commit.
Pick Resend if you want the best developer experience for a new product and can accept a younger provider. Pick Postmark if deliverability is the whole job and you want the most conservative reputation model in the market. Either way, the SPF, DKIM and DMARC records on your domain decide most of the outcome.
Whichever provider you pick, the setup on your domain decides the outcome.
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