User guide

API reference


Sandbox mode

Sandbox mode allows you to safely test out different parts of Postmark without accidentally sending email to real recipients. This helps you integrate Postmark with your CI processes, learn how our API works, experiment with webhooks, and more—all in a safe space that’s designed for testing and experimentation.

❗️ Good to know: Even though test messages aren’t delivered to real inboxes, we still process them through Postmark’s infrastructure and our API remains accessible for these messages. That’s why emails sent through Sandbox Servers do count towards your monthly sending volume.