action-mailer-coder

Parameterized mailers use Rails' with() method to pass variables into mailer actions. Define a mailer class, accept parameters via with(user:, account:), and reference them in your email templates. This approach isolates email logic and makes testing straightforward.

Yes. Rails Action Mailer includes a preview system that renders emails in your browser without sending. Create a preview class, define preview methods returning mailer calls, and access them at /rails/mailers to visually test designs, content, and localization.

Use deliver_later instead of deliver_now to push email delivery to a background job queue. This keeps your request cycle fast and lets you retry failed sends. Pair it with Active Job and a job backend like Sidekiq or Resque for production reliability.

Use Rails i18n helpers (I18n.locale, t()) in mailer templates to translate email content. Attach files via the attachments hash, referencing file paths or inline blobs. Combine both to send localized emails with dynamic documents to users worldwide.

Yes. RSpec supports mailer specs via have_enqueued_mail and deliver matchers. Assert on recipient, subject, body content, and attachments. Test parameterized calls, background delivery jobs, and preview classes to ensure email logic stays correct across changes.

Rails 7.1+ introduces refined parameterized mailer syntax, improved preview workflows, and streamlined background delivery conventions. Earlier versions support core features but lack convenience methods and cleaner patterns for grouping mailer logic and inheritance.