With Postmark, a day doesn't go by that I don't think to myself how simple it is to use it and how fast you can start sending emails. Simple, easy, fast - three words which are our top priority goals. Achieving all three, especially sending emails fast comes with a price: reliability. From day one, our goal has been to deliver email to you reliably. Losing emails or emails not reaching your inbox has never been an option. We have been working very hard to maintain this by writing automated tests for Postmark using tools like Selenium, Jenkins, and Statsd/Librato. The first tests written covered sending email by SMTP and the API, tracking how long it takes to send and receive emails. Once these were in place, we extended the test suite with Inbound tests, Bounce API, and UI tests. We run these tests frequently using a dedicated Jenkins machine on a Linux server, allowing us to gain more feedback from Postmark. We also use Selenium Grid and Jenkins nodes to run tests in parallel, enabling faster running of top priority tests. With Librato, we can track performance history for search, bounce API calls, and inbound processing, providing valuable insights into our testing process.