The Multi-Environment Challenge
Modern teams run multiple environments in parallel — local dev, feature branches, staging, and production. Each environment sends emails: welcome messages, password resets, notifications, reports. When all environments share one inbox, it becomes impossible to tell which email came from where.
The solution
Register one subdomain per environment on OpenInbox: staging.yourdomain.com, dev.yourdomain.com, qa.yourdomain.com. Each subdomain counts as one custom domain toward your plan limit.
Recommended Architecture
yourdomain.com ← production mail (your mail provider) staging.yourdomain.com ← MX → OpenInbox (custom domain #1) dev.yourdomain.com ← MX → OpenInbox (custom domain #2) qa.yourdomain.com ← MX → OpenInbox (custom domain #3) Staging app sends to: [email protected] Dev app sends to: [email protected] QA suite sends to: [email protected]
Your production domain stays on your normal mail provider (Google Workspace, Microsoft 365, etc.). Only the testing subdomains point to OpenInbox. This gives you full isolation with zero risk to production email.
Step-by-Step Setup
Add the subdomain in OpenInbox
Go to Settings → Domains → Add Domain. Enter staging.yourdomain.com.
Add DNS records for the subdomain
At your registrar, create an MX record for staging.yourdomain.com and the three DKIM CNAME records shown in the dashboard.
Verify & activate
Click "Verify DNS". Once all records resolve, the subdomain is ready.
Point your staging app at the subdomain
Update your staging app's email config so it sends to addresses like [email protected].
Create inboxes as needed
Use the API or UI to create temporary inboxes on the subdomain — they auto-expire as usual.
Benefits of Per-Environment Subdomains
Complete Isolation
Staging emails never mix with dev emails. Debugging is instant — just check the right subdomain.
Production Safety
Your production MX records are untouched. Only test subdomains route to OpenInbox.
Easy Cleanup
Remove the subdomain from OpenInbox when the project ends. DNS records can be deleted at your registrar.
Team Visibility
Anyone on the team can check the inbox for their environment without access to another team's emails.
Practical Tips
- Use a Pro ($7/mo) or Business ($15/mo) plan to register multiple subdomains (3 or 10 domains).
- Name subdomains after branches for feature-flag environments: feat-auth.yourdomain.com.
- Automate inbox creation in your CI pipeline — the OpenInbox API supports specifying a domain ID at creation time.
- Monitor your monthly email quota on the Settings → Domains page to avoid hitting limits mid-sprint.
- Combine with webhooks to trigger test assertions immediately when an email arrives.
Isolate Your Environments Today
Pick a plan with multi-domain support and set up per-environment subdomains in minutes.
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