SendGrid gem provides ActionMailer::Base extensions to use SendGrid API features in you emails. It extends ActionMailer with next methods:

substitute(patters_string, array_of_substitunion_strings)
uniq_args(hash_of_unique_args)
category(category_string)
open_tracking(enabled = true)
add_filter_setting(filter_name, setting_name, value)

In your Gemfile:

gem 'sendgrid-rails', '~> 2.0'

In config/initializers/mail.rb:

ActionMailer::Base.register_interceptor(SendGrid::MailInterceptor)

ActionMailer::Base.smtp_settings = {
  :address => 'smtp.sendgrid.net',
  :port => '25',
  :domain => 'example.com',
  :authentication => :plain,
  :user_name => '[email protected]',
  :password => 'your password'
}

class Mailer < ActionMailer::Base
  default :from => '[email protected]',
          :subject => 'An email sent via SendGrid'

  def email_with_multiple_recipients
    mail :to => %w([email protected] [email protected])
  end
end

Mailer class definition:

class Mailer < ActionMailer::Base
  default :from => '[email protected]',
          :subject => 'An email sent via SendGrid with substitutions'

  def email_with_substitutions
    substitute '-user_name-', %w(User1 User2)

    mail :to => %w([email protected] [email protected]), :body => "Hello, -user_name-!"
  end
end

Mailer class definition:

class Mailer < ActionMailer::Base
  default :from => '[email protected]',
          :subject => 'An email sent via SendGrid with substitutions'

  def email_with_category
    category 'SendGridRocks'
    mail :to => '[email protected]'
  end
end

Apps can be applied to any of your email messages and can be configured through SendGrid gem.

Add an invisible image at the end of the email to track e-mail opens. If the email recipient has images enabled on the email client, a request to server for the invisible image is executed and an open is logged.

class Mailer < ActionMailer::Base
  default :from => '[email protected]',
          :subject => 'An email sent via SendGrid'

  def email_with_open_tracking_enabled
    open_tracking true
    mail :to => '[email protected]'
  end
end

v2.0.2

• ApiHeader#to_json wraps array items with spaces

v2.0.1

• Standard SMTP To attribute set to ‘[email protected]’ after recipients added to X-SMTPAPI header

v2.0

• Using mail interceptor

• ActionMailer::Base#add_recipients - removed

• Standard SMTP To attribute get nullified after recipients added to X-SMTPAPI header