Rails ActionMailer with multiple SMTP servers

Question

I have a need to use two different smtp servers in a Rails application. It appears that the way ActionMailer is constructed, it is not possible to have different smtp_settings for a subclass. I could reload the smtp settings for each mailer class whenever a message is being sent, but that messes up the ExceptionNotifier plugin which is outside my control (unless I mess with it too). Does anyone have a solution/plugin for something like this?

Ideally I would like to have

class UserMailer < ActionMailer::Base; end

and then set in environment.rb

ActionMailer::Base.smtp_settings = standard_smtp_settings
UserMailer.smtp_settings = user_smtp_settings

Thus, most of my mailers including ExceptionNotifier would pickup the default settings, but the UserMailer would use a paid relay service.

Answer 1

Rails-2.3.*

# app/models/user_mailer.rb
class UserMailer < ActionMailer::Base
  def self.smtp_settings
    USER_MAILER_SMTP_SETTINGS
  end

  def spam(user)
    recipients user.mail
    from '[e-mail]'
    subject 'Enlarge whatever!'
    body :user => user
    content_type 'text/html'
  end
end

# config/environment.rb
ActionMailer::Base.smtp_settings = standard_smtp_settings
USER_MAILER_SMTP_SETTINGS = user_smtp_settings

# From console or whatever...
UserMailer.deliver_spam(user)

Answer 2

Based on the Oreilly article, I came up with the solution I wrote about here: http://transfs.com/devblog/2009/12/03/custom-smtp-settings-for-a-specific-actionmailer-subclass

Here's the relevant code:

class MailerWithCustomSmtp < ActionMailer::Base
  SMTP_SETTINGS = {
    :address => "smtp.gmail.com",
    :port => 587,
    :authentication => :plain,
    :user_name => "[e-mail]",
    :password => 'password',
  }

  def awesome_email(bidder, options={})
     with_custom_smtp_settings do
        subject       'Awesome Email D00D!'
        recipients    '[e-mail]'
        from          '[e-mail]'
        body          'Hope this works...'
     end
  end

  # Override the deliver! method so that we can reset our custom smtp server settings
  def deliver!(mail = @mail)
    out = super
    reset_smtp_settings if @_temp_smtp_settings
    out
  end

  private

  def with_custom_smtp_settings(&block)
    @_temp_smtp_settings = @@smtp_settings
    @@smtp_settings = SMTP_SETTINGS
    yield
  end

  def reset_smtp_settings
    @@smtp_settings = @_temp_smtp_settings
    @_temp_smtp_settings = nil
  end
end

Answer 3

Here's another solution, which, while it looks ridiculous, I think is a little bit cleaner and easier to reuse in different AM::Base classes:

    module FTTUtilities
      module ActionMailer
        module ClassMethods
          def smtp_settings
            dict = YAML.load_file(RAILS_ROOT + "/config/custom_mailers.yml")[self.name.underscore]
            @custom_smtp_settings ||= HashWithIndifferentAccess.new(dict)
          end
        end

        module InstanceMethods
          def smtp_settings
            self.class.smtp_settings
          end
        end
      end
    end

example Mailer:

    class CustomMailer < ActionMailer::Base
        extend FTTUtilites::ActionMailer::ClassMethods
        include FTTUtilites::ActionMailer::InstanceMethods
    end

Answer 4

class UserMailer < ActionMailer::Base
  def welcome_email(user, company)
    @user = user
    @url  = user_url(@user)
    delivery_options = { user_name: company.smtp_user,
                         password: company.smtp_password,
                         address: company.smtp_host }
    mail(to: @user.email,
         subject: "Please see the Terms and Conditions attached",
         delivery_method_options: delivery_options)
  end
end

Rails 4 allows for dynamic delivery options. The above code is straight from the action mailer basics guide, which you can find here: http://guides.rubyonrails.org/v4.0/action_mailer_basics.html#sending-emails-with-dynamic-delivery-options

With this, it is possible to have different smtp settings for every email you send, or, like in your use case for different sub classes like UserMailer, OtherMailer etc.

Answer 5

Solution for Rails 3.2:

class SomeMailer < ActionMailer::Base

  include AbstractController::Callbacks
  after_filter :set_delivery_options

  private
  def set_delivery_options
    settings = {
      :address => 'smtp.server',
      :port => 587,
      :domain => 'your_domain',
      :user_name => 'smtp_username',
      :password => 'smtp_password',
      :authentication => 'PLAIN' # or something
    }

    message.delivery_method.settings.merge!(settings)
  end
end

Solution inspired by How to send emails with multiple, dynamic smtp using Actionmailer/Ruby on Rails

Answer 6

Tried to use jkrall's option with Rails 3.2.1 but for some reason it wouldn't override default configuration, but doing:

MyMailer.my_email.delivery_method.settings.merge!(SMTP_SETTINGS).deliver

Similar to http://www.scottw.com/multiple-smtp-servers-with-action-mailer, made it work.