SKILL.md
Mailtrap Email Integration
Patterns for adding transactional email sending to an application using Mailtrap's Email API and Sandbox, covering authentication, environment separation, and common delivery pitfalls.
When to Activate
- Implementing a "send email" feature (signup confirmation, password reset, notifications, receipts)
- Debugging why emails aren't arriving in dev/staging
- Setting up a project's first email-sending integration
- Reviewing code that calls an email API directly without sandbox separation
Core Concepts
Sandbox vs. Production separation. Mailtrap provides a Sandbox API that captures emails without delivering them, used for dev/staging so test emails never reach real inboxes. Production sending uses a separate, verified-domain endpoint. Never point a dev environment at the production sending endpoint.
Authentication. Requests use a Bearer token in the Authorization header. Tokens are scoped per project; sandbox and production typically use different tokens.
Domain verification. Production sending requires verifying a sending domain via DNS records (SPF, DKIM, DMARC) before Mailtrap will deliver to real recipients. Skipping this causes silent delivery failures or spam-folder placement.