Postmark

Postmark launched in 2010 with a focus on reliable transactional email delivery. The free plan includes 100 emails per month, intended mainly for testing and small-scale sending. Postmark's API and SMTP integration are built for developers who need bulletproof delivery rates and detailed analytics.

Choose Postmark if transactional email reliability is your priority. This isn't a newsletter platform; it's a developer tool for password resets, confirmations, and notifications where delivery matters absolutely.