= SendGrid SMTP API gem for Rails

SendGrid SMTP API 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)
		standard_smtp(enabled = true)

== Rails 3 configuration

In your Gemfile:

    gem 'sendgrid_smtpapi'

In your config/environment.rb:

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

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

== Usage examples

=== Adding multiple recipients:

    class Mailer < ActionMailer::Base
      default :from => 'no-reply@example.com',
              :subject => 'An email sent via SendGridSmtpApi'

      def email_with_multiple_recipients
        mail :to => %w(email1@email.com email2@email.com)
      end
    end

=== Adding substitution vars

Mailer class definition:

    class Mailer < ActionMailer::Base
      default :from => 'no-reply@example.com',
              :subject => 'An email sent via SendGridSmtpApi with substitutions'

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

        mail :to => %w(email1@email.com email2@email.com), :body => "Hello, -user_name-!"
      end
    end

=== Adding category

    Mailer class definition:

        class Mailer < ActionMailer::Base
          default :from => 'no-reply@example.com',
                  :subject => 'An email sent via SendGridSmtpApi with substitutions'

          def email_with_category
            category 'SendGridSmtpApiRocks'
            mail :to => 'email1@email.com'
          end
        end

== Apps (formerly called Filters)

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

=== Open Tracking

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 => 'no-reply@example.com',
              :subject => 'An email sent via SendGridSmtpApi'

      def email_with_open_tracking_enabled
        open_tracking true
        mail :to => 'email@email.com'
      end
    end


=== Use Standard SMTP

if you want to customize the header for sendgrids api but you need keep standard SMTP see below:

    class Mailer < ActionMailer::Base
      default :from => 'no-reply@example.com',
              :subject => 'An email sent via SendGridSmtpApi'

      def email_standard_smtp
        standard_smtp true
        open_tracking true
        mail :to => 'email@email.com'
      end
    end