5 files changed, 27 insertions, 15 deletions
diff --git a/actionmailer/lib/action_mailer.rb b/actionmailer/lib/action_mailer.rb
index 8e59f033d0..8eba811ab6 100644
--- a/actionmailer/lib/action_mailer.rb
+++ b/actionmailer/lib/action_mailer.rb
@@ -22,7 +22,7 @@
 #++
 
 require "abstract_controller"
-require "action_mailer/version"
+require_relative "action_mailer/version"
 
 # Common Active Support usage in Action Mailer
 require "active_support"
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 7133670b65..2b4992791d 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -1,11 +1,11 @@
 require "mail"
-require "action_mailer/collector"
+require_relative "collector"
 require "active_support/core_ext/string/inflections"
 require "active_support/core_ext/hash/except"
 require "active_support/core_ext/module/anonymous"
 
-require "action_mailer/log_subscriber"
-require "action_mailer/rescuable"
+require_relative "log_subscriber"
+require_relative "rescuable"
 
 module ActionMailer
   # Action Mailer allows you to send email from your application using a mailer model and views.
@@ -459,6 +459,7 @@ module ActionMailer
 
     helper ActionMailer::MailHelper
 
+    class_attribute :delivery_job, default: ::ActionMailer::DeliveryJob
     class_attribute :default_params, default: {
       mime_version: "1.0",
       charset:      "UTF-8",
diff --git a/actionmailer/lib/action_mailer/delivery_methods.rb b/actionmailer/lib/action_mailer/delivery_methods.rb
index afdc28aa2a..93ae10fd70 100644
--- a/actionmailer/lib/action_mailer/delivery_methods.rb
+++ b/actionmailer/lib/action_mailer/delivery_methods.rb
@@ -8,14 +8,9 @@ module ActionMailer
 
     included do
       # Do not make this inheritable, because we always want it to propagate
-      cattr_accessor :raise_delivery_errors
-      self.raise_delivery_errors = true
-
-      cattr_accessor :perform_deliveries
-      self.perform_deliveries = true
-
-      cattr_accessor :deliver_later_queue_name
-      self.deliver_later_queue_name = :mailers
+      cattr_accessor :raise_delivery_errors, default: true
+      cattr_accessor :perform_deliveries, default: true
+      cattr_accessor :deliver_later_queue_name, default: :mailers
 
       class_attribute :delivery_methods, default: {}.freeze
       class_attribute :delivery_method, default: :smtp
diff --git a/actionmailer/lib/action_mailer/message_delivery.rb b/actionmailer/lib/action_mailer/message_delivery.rb
index cf7c57e6bf..0b54e12431 100644
--- a/actionmailer/lib/action_mailer/message_delivery.rb
+++ b/actionmailer/lib/action_mailer/message_delivery.rb
@@ -51,6 +51,14 @@ module ActionMailer
     #   Notifier.welcome(User.first).deliver_later!(wait: 1.hour)
     #   Notifier.welcome(User.first).deliver_later!(wait_until: 10.hours.from_now)
     #
+    # By default, the email will be enqueued using <tt>ActionMailer::DeliveryJob</tt>. Each
+    # <tt>ActionMailer::Base</tt> class can specify the job to use by setting the class variable
+    # +delivery_job+.
+    #
+    #   class AccountRegistrationMailer < ApplicationMailer
+    #     self.delivery_job = RegistrationDeliveryJob
+    #   end
+    #
     # Options:
     #
     # * <tt>:wait</tt> - Enqueue the email to be delivered with a delay
@@ -67,6 +75,14 @@ module ActionMailer
     #   Notifier.welcome(User.first).deliver_later(wait: 1.hour)
     #   Notifier.welcome(User.first).deliver_later(wait_until: 10.hours.from_now)
     #
+    # By default, the email will be enqueued using <tt>ActionMailer::DeliveryJob</tt>. Each
+    # <tt>ActionMailer::Base</tt> class can specify the job to use by setting the class variable
+    # +delivery_job+.
+    #
+    #   class AccountRegistrationMailer < ApplicationMailer
+    #     self.delivery_job = RegistrationDeliveryJob
+    #   end
+    #
     # Options:
     #
     # * <tt>:wait</tt> - Enqueue the email to be delivered with a delay.
@@ -118,7 +134,8 @@ module ActionMailer
             "method*, or 3. use a custom Active Job instead of #deliver_later."
         else
           args = @mailer_class.name, @action.to_s, delivery_method.to_s, *@args
-          ::ActionMailer::DeliveryJob.set(options).perform_later(*args)
+          job = @mailer_class.delivery_job
+          job.set(options).perform_later(*args)
         end
       end
   end
diff --git a/actionmailer/lib/action_mailer/preview.rb b/actionmailer/lib/action_mailer/preview.rb
index 87ba743f3d..4f72eca930 100644
--- a/actionmailer/lib/action_mailer/preview.rb
+++ b/actionmailer/lib/action_mailer/preview.rb
@@ -20,8 +20,7 @@ module ActionMailer
       mattr_accessor :show_previews, instance_writer: false
 
       # :nodoc:
-      mattr_accessor :preview_interceptors, instance_writer: false
-      self.preview_interceptors = [ActionMailer::InlinePreviewInterceptor]
+      mattr_accessor :preview_interceptors, instance_writer: false, default: [ActionMailer::InlinePreviewInterceptor]
     end
 
     module ClassMethods