What'll we learn:

• Introduction to Action Mailer
• Create an Action Mailer
• Action Mailer Preview
• Configuration
• Integrate with SendGrid
• Conclusion

Introduction to Action Mailer

• Action Mailer is a component in Ruby on Rails that allows you to send emails from your Rails application.
• Action Mailer works similar to Controller, that means Mailers have:
  • Actions, and associated views that appear in app/views.
  • Instance variables that are accessible in views.
  • The ability to utilize layouts and partials.
  • The ability to access a params hash.

Create an Action Mailer

rails generate mailer Subscriber
Running via Spring preloader in process 7586
      create  app/mailers/subscriber_mailer.rb
      invoke  erb
      create    app/views/subscriber_mailer
      invoke  test_unit
      create    test/mailers/subscriber_mailer_test.rb
      create    test/mailers/previews/subscriber_mailer_preview.rb

• SubscriberMailer: app/mailers/subscriber_mailer.rb
• SubscriberMailerPreview: test/mailers/previews/subscriber_mailer_preview.rb

class SubscriberMailer < ApplicationMailer
end

# Preview all emails at http://localhost:3000/rails/mailers/subscriber_mailer
class SubscriberMailerPreview < ActionMailer::Preview
end

Create a Welcome Email

class SubscriberMailer < ApplicationMailer
  def welcome_email(subscriber)
    @subscriber = subscriber

    mail(
      from:    'Luan Nguyen <[email protected]>',
      to:      @subscriber.email,
      subject: 'Welcome to FullstackRubyonRails.com'
    )
  end
end

# app/views/subscriber_mailer/welcome_email.html.erb
<p>Hi <%= @subscriber.name %></p>
<p>Thanks for subscribing to our newsletters!</p>
<br>
<p>Cheers,</p>
<p>Luan Nguyen</p>

Update in Subscriber Mailer Preview

# Preview all emails at http://localhost:3000/rails/mailers/subscriber_mailer
class SubscriberMailerPreview < ActionMailer::Preview
  def welcome_email
    subscriber = Subscriber.find_or_create_by(
      name: "User", 
      email: '[email protected]'
    )
    SubscriberMailer.welcome_email(subscriber)
  end
end

Access to http://localhost:3000/rails/mailers/subscriber_mailer/welcome_email to preview welcome_email email in browser. The email looks like:

Calling the Mailer

SubscriberMailer.welcome_email(subscriber).deliver_now

SubscriberMailer.welcome_email(subscriber).deliver_later

Action Mailer Configuration

• In Development environment (config/environments/development.rb)

config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }
config.action_mailer.delivery_method    = :letter_opener
config.action_mailer.perform_deliveries = true

• In Production environment (config/environments/production.rb)

config.action_mailer.default_url_options = { host: 'you-domain.com' }
config.action_mailer.delivery_method     = :smtp
config.action_mailer.smtp_settings       = {
  authentication: :plain,
  address:        'smtp.sendgrid.net',
  port:           587,
  user_name:      SENDGRID_NAME_KEY,
  password:       SENDGRID_API_KEY,
  domain:         'you-domain.com'
}

Integrating with Sendgrid SMTP API:

1. Create an account in Sendgrid.
2. Navigate to Settings on the left navigation bar, and then select API Keys.
3. Click Create API Key.
4. Give your API key a name.
5. Select Full Access, Restricted Access, or Billing Access.
   • Full Access allows the API key to access GET, PATCH, PUT, DELETE and POST endpoints for all parts of your account, excluding billing and Email Address Validation.
   • Restricted Access customizes levels of access for all parts of your account, excluding billing and Email Address Validation.
   • Billing Access allows the API key to access billing endpoints for the account.
6. Click Create & View

• user_name: SENDGRID_NAME_KEY 
• password:  SENDGRID_API_KEY  

Conclusion