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Action Mailer in Rails

What is Action Mailer?

Action Mailer is part of the Rails framework and is designed to make it incredibly simple to send emails from a Rails application. It works very much like Action Controller, providing controllers and views for creating an email message. Essentially, it renders and sends the email.

Generating a Mailer

To send an email with Action Mailer, the first step is to generate a Mailer. This can be done using a generator or by manually creating a file inside app/mailers. The Mailer has a similar structure to controllers, where individual methods correspond to specific emails your application can send.

Mailer Views

Once the Mailer is generated, the next step is creating its views. For instance, if a Mailer has a method called ‘welcome_email’, then the corresponding view file would be app/views/user_mailer/welcome_email.html.erb for the HTML version.

The system handles multipart emails automatically, generating both a text and HTML email from the same template without any additional setup.

Delivering Emails

The delivery of emails can be handled asynchronously or synchronously, through deliver_later and deliver_now respectively. The deliver_later method enqueues the email to be sent using Active Job’s async adapter, while deliver_now sends the email immediately.

Enhancing Rails Mailers


Rails Mailers supports automatic encoding of attachments and multi-part emails. To add an attachment to your email, you call the attachments method on the Mail instance.

Email Previews

Action Mailer features a ‘preview’ system that allows developers to preview their emails in the browser without having to send them. By default, these preview classes live in test/mailers/previews. This can be quite handy for quickly iterating on your email templates.

Helpers and Callbacks

Just like Action Controller, Action Mailer allows you to use helper methods and callbacks. These can aid in setting up common features or behaviors for your mailers. These can be specified with a block or a symbol referencing a method in the Mailer class.

Mailer Settings and Configurations

Action Mailer uses the Mail gem and accepts similar configuration settings. These configurations can be overridden for individual mailers if needed. If using Gmail for sending emails, remember to set an app password if you have enabled 2-factor authentication.

Using Rails Mailers Responsibly

Considering Your Audience

Remember that while Action Mailer offers many tools and techniques for delivering emails, you should tailor all emails to the specific needs and preferences of your users. Some users may not prefer HTML emails, so it’s a good practice to provide both HTML and plain text versions.

Email Observers

Action Mailer offers hooks into the email delivery life cycle, enabling us to observe and intercept emails before sending them. These hooks prove valuable for making last-minute modifications to emails or tracking email delivery statistics.

Conclusion: Wrapping Up Rails Mailers

The Rails Mailer is a powerful, flexible component of the Rails framework. It simplifies the process of sending both simple and complex emails and allows integration with Active Job for asynchronous delivery. Although not without its complexities, Rails Mailer manages to provide a clean, intuitive API for delivering emails in a Rails application.

Hope this article helped improve your understanding of Rails Mailers. Revisit the previous article on the Rails Assets Pipeline, and stay tuned for more articles on Ruby on Rails.


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