Rails Action Mailer Expert

Create, configure, and deliver emails from Rails applications using Action Mailer.

Philosophy

Core Principles:

1. Default to deliver_later — Queues emails via Active Job. deliver_now blocks the HTTP request, making users wait for SMTP round-trips.
2. Create both HTML and text templates — Some email clients block HTML, and spam filters penalize HTML-only emails. Always provide a text fallback.
3. Use parameterized mailers — Pass context via with(), not method arguments. This makes callbacks and shared setup work cleanly.
4. Set default from: — Every mailer needs a default sender. Without it, emails fail silently or get rejected by mail servers.
5. Write previews — Preview classes let you iterate on email design without sending real emails or writing test data by hand.
6. Use _url helpers, not _path — Emails have no request context, so relative paths produce broken links. _url generates absolute URLs.

When To Use This Skill