Postmark

Postmark was built by Wildbit, a small product studio that had already been running for years before deciding transactional email deserved a company of its own. It launched around 2010 and stayed independent for over a decade before ActiveCampaign bought it in 2022, folding it into a broader marketing stack while, to Postmark's credit, mostly leaving the product alone. The pitch from day one was narrow on purpose: send transactional email fast, and refuse to touch anything that looks like a bulk marketing blast.

That refusal is enforced, not just marketed, though none of it has anything to do with AI. Postmark splits your account into separate message streams for transactional and broadcast mail, and if their system catches you routing newsletter-style sends through the transactional stream, it will flag or suspend the account rather than let it slide. That's an inconvenience if you didn't read the fine print, and a selling point if you did, since it's exactly what keeps a stranger's spam campaign from tanking the deliverability of your password reset emails. The tradeoff is that there's no meaningful free tier beyond a small batch of test sends, and if you want marketing email tools you'll need a different product entirely. That's by design, and it's why developers who've been burned by shared-IP reputation problems elsewhere tend to become loyal, sometimes vocal, fans.