Guides / Ruby on Rails

Test Ruby on Rails emails locally

RustMail is a local SMTP mail catcher. Your Ruby app keeps sending mail the way it does in production, and every message lands in a web UI instead of a real inbox. Four steps, about two minutes.

1. 1

   Start RustMail

   One container, SMTP on port 1025 and the web UI on 8025.

   docker run -p 1025:1025 -p 8025:8025 smyile/rustmail:latest

2. 2

   Point Ruby on Rails at it

   In config/environments/development.rb, send mail to localhost:1025 with no TLS and no credentials.

   config.action_mailer.delivery_method = :smtp
   config.action_mailer.smtp_settings = {
     address: "localhost",
     port: 1025
   }

3. 3

   Send a test email

   Then open localhost:8025: the message is already in the inbox, with its HTML, headers and links.

   bin/rails runner 'ActionMailer::Base.mail(from: "[email protected]", to: "[email protected]", subject: "Welcome", body: "Hello from Rails").deliver_now'

4. 4

   Assert on it in CI

   In GitHub Actions, start RustMail, run tests that send mail with the config/environments/development.rb settings from step 2, then fail the job when the email never arrives.

   - name: Start RustMail on localhost:1025
     uses: rustmailapp/rustmail-action@v1
     with:
       mode: start
   
   - name: Run the tests that send mail over SMTP
     run: bin/rails test:system
   
   - name: Fail if the welcome email never arrived
     uses: rustmailapp/rustmail-action@v1
     with:
       mode: assert
       assert-count: 1
       assert-subject: "Welcome"