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_settin

Answer 1

https://github.com/AnthonyCaliendo/action_mailer_callbacks

I found this plugin helped solve the problem for me pretty easily (as in < 5 mins). I simply change the @@smtp_settings for a particular mailer in the before_deliver and then change it back to the defaults in the after_deliver. Using this approach, I only have to add the callbacks to mailers that need @@smtp_settings different than the default.

class CustomMailer < ActionMailer::Base

  before_deliver do |mail|
    self.smtp_settings = custom_settings
  end

  after_deliver do |mail|
    self.smtp_settings = default_settings
  end

  def some_message
    subject "blah"
    recipients "blah@blah.com"
    from "ruby.ninja@ninjaness.com"
    body "You can haz Ninja rb skillz!"
    attachment some_doc
  end

end

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 => "custom_account@transfs.com",
    :password => 'password',
  }

  def awesome_email(bidder, options={})
     with_custom_smtp_settings do
        subject       'Awesome Email D00D!'
        recipients    'someone@test.com'
        from          'custom_reply_to@transfs.com'
        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

For anybody approaching this issue with later versions (3+) of Rails, try this

http://guides.rubyonrails.org/action_mailer_basics.html#sending-emails-with-dynamic-delivery-options

Answer 4

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 5

Solution for Rails 4.2+:

config/secrets.yml:

production:
  gmail_smtp:
    :authentication: "plain"
    :address: "smtp.gmail.com"
    :port: 587
    :domain: "zzz.com"
    :user_name: "zzz@zzz.com"
    :password: "zzz"
    :enable_starttls_auto: true
  mandrill_smtp:
    :authentication: "plain"
    :address: "smtp.mandrillapp.com"
    :port: 587
    :domain: "zzz.com"
    :user_name: "zzz@zzz.com"
    :password: "zzz"
    :enable_starttls_auto: true
  mailgun_smtp:
    :authentication: "plain"
    :address: "smtp.mailgun.org"
    :port: 587
    :domain: "zzz.com"
    :user_name: "zzz@zzz.com"
    :password: "zzz"
    :enable_starttls_auto: true

config/environments/production.rb:

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = Rails.application.secrets.gmail_smtp

app/mailers/application_mailer.rb:

class ApplicationMailer < ActionMailer::Base
  default from: '"ZZZ" <zzz@zzz.com>'

  private

  def gmail_delivery
    mail.delivery_method.settings = Rails.application.secrets.gmail_smtp
  end

  def mandrill_delivery
    mail.delivery_method.settings = Rails.application.secrets.mandrill_smtp
  end

  def mailgun_delivery
    mail.delivery_method.settings = Rails.application.secrets.mailgun_smtp
  end
end

app/mailers/user_mailer.rb:

class UserMailer < ApplicationMailer
  # after_action :gmail_delivery, only: [:notify_user]
  after_action :mandrill_delivery, only: [:newsletter]
  after_action :mailgun_delivery, only: [:newsletter2]

  def newsletter(user_id); '...' end # this will be sent through mandrill smtp
  def newsletter2(user_id); '...' end # this will be sent through mailgun smtp
  def notify_user(user_id); '...' end # this will be sent through gmail smtp
end