Mailgun

Build with the platform that enables you to send, track, and optimize email from code.

Mailgun is the email API for developers that helped define the category: a sending API with validation, inbound routing and parse, templates, analytics and log retention long enough to debug delivery, now part of Sinch. It is the workhorse choice for transactional email at product scale.

Why founders use it: the API is boring in the good way, send, validate, receive routes, with SDKs everywhere and predictable behavior under load. Inbound email with parse-to-webhook powers reply-by-email features that most competitors make awkward, and the deliverability tooling, dedicated IPs, reputation dashboards, is there when volume grows.

A realistic setup: domain verification, transactional sends via API with templates, a webhook writing delivery and bounce events, inbound routes forwarding replies into the product, and suppression management honored automatically.

Trade-offs: pricing now scales through tiers and add-ons that need reading twice, and the free tier is trial-shaped rather than a permanent home. Compare with Postmark for deliverability support culture, Resend for the modern DX, and Amazon SES for raw cost at volume.