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Email

Mailgun

Transactional email API and SMTP relay for developers with powerful sending, validation, and deliverability tools.

Sending transactional emails (password resets, order confirmations) from a SaaS application
Integrating email sending into a CI/CD pipeline for deployment notifications
Running a small newsletter with automated welcome sequences for new signups

100 emails/day, 1 custom domain, RESTful API and SMTP, basic analytics

The free tier gives 100 emails/day — perfect for transactional use cases. Use the REST API over SMTP for better tracking and reliability. Configure SPF/DKIM/DMARC to protect deliverability. Monitor usage daily since the cap blocks sends silently. One domain only, so pick the one that matters most.

Sign up for a free account → verify your email → add and verify your sending domain (configure SPF, DKIM, DMARC records in DNS) → get your API key or SMTP credentials → integrate via the REST API or SMTP relay → send a test email and check delivery in the dashboard.

Pros

  • Developer-first API: Clean REST API with comprehensive SDKs for Python, Ruby, Node.js, PHP, and Go — built for integration, not point-and-click
  • Deliverability tools: Built-in email validation, bounce classification, and suppression management help maintain sender reputation
  • SMTP + API flexibility: Supports both SMTP relay and HTTP API so you can choose the method that fits your stack

Cons

  • Strict free tier: 100 emails/day with no option to burst — a single viral notification can exhaust your quota for the day
  • Limited retention: Only 1 day of log retention on the free tier makes debugging delivery issues difficult
  • Account approval: New accounts require manual approval before sending, which can delay your first campaign by hours