Transactional emails are the plumbing of your SaaS—password resets, login codes, onboarding emails, invoices, and critical alerts. When they arrive late (or not at all), users churn, support tickets spike, and your product feels unreliable—even if everything else works perfectly.
This guide is built for SaaS and developer teams who want a production-ready approach to transactional email APIs. You’ll learn how to authenticate your sending domain, integrate an email API securely, track delivery events, and troubleshoot failures using logs instead of guesswork.
Whether you’re sending 500 emails a day or launching to 500,000 users, this step-by-step guide covers the fundamentals that scale—plus the common mistakes behind “it says sent, but I never received it” issues. No inbox myths. Just systems that work. Start Free Trail — send your first transactional email in under 5 minutes.
- Verify your sending domain (SPF + DKIM, ideally DMARC) before scaling password resets or OTPs.
- Keep API keys server-side only —never expose them in frontend code.
- Use provider logs and event tracking to debug missing emails fast.
- Retry only transient failures (429 / 5xx), not configuration errors (401 / 403).
- If reputation and volume matter, plan early for dedicated infrastructure.
