When to use a Sandbox Channel
Sandbox Channels are good for:- Building your integration - Test your API calls, SMTP setup, and payload formatting without worrying about test emails landing in someone’s inbox.
- Checking templates - Send real messages through the API and inspect them in the Helo dashboard to confirm they are working correctly.
- Testing webhooks — Sandbox messages trigger delivery webhooks just like live messages do, so you can build and test your webhook handlers end-to-end.
- Supporting QA and staging environments — Point your staging app at a Sandbox Channel so your team can test freely without any risk.
Tip: Create API credentials that work with your Sandbox Channel. When setting up new API credentials, you can decide to scope them to a single Channel only. Set up dedicated credentials that work with your Sandbox environment only to further isolate your testing environments.
How Sandbox Channels work
Sandbox Channels process messages through Helo’s infrastructure the same way live sends do. That means:- Messages show up as Delivered in your dashboard and via the API (even though we don’t actually deliver them to real inboxes)
- All message metadata (headers, recipient, subject, body) is stored and inspectable
- Delivery webhooks fire normally
- Bounce simulation is supported (see simulating bounces)
Heads up: Because Sandbox messages are processed through Helo’s infrastructure, they do count toward your monthly sending budget, just like live messages.