Index: app/models/mailer.rb
===================================================================
--- app/models/mailer.rb	(revision 19478)
+++ app/models/mailer.rb	(working copy)
@@ -624,13 +624,13 @@
   # Rake will likely end, causing the in-process thread pool to be deleted, before
   # any/all of the .deliver_later emails are processed
   def self.with_synched_deliveries(&block)
-    adapter = ActionMailer::DeliveryJob.queue_adapter
+    adapter = ActionMailer::MailDeliveryJob.queue_adapter
     if adapter.is_a?(ActiveJob::QueueAdapters::AsyncAdapter)
-      ActionMailer::DeliveryJob.queue_adapter = ActiveJob::QueueAdapters::InlineAdapter.new
+      ActionMailer::MailDeliveryJob.queue_adapter = ActiveJob::QueueAdapters::InlineAdapter.new
     end
     yield
   ensure
-    ActionMailer::DeliveryJob.queue_adapter = adapter
+    ActionMailer::MailDeliveryJob.queue_adapter = adapter
   end
 
   def mail(headers={}, &block)
Index: config/application.rb
===================================================================
--- config/application.rb	(revision 19478)
+++ config/application.rb	(working copy)
@@ -33,6 +33,8 @@
     config.active_record.store_full_sti_class = true
     config.active_record.default_timezone = :local
 
+    config.action_mailer.delivery_job = "ActionMailer::MailDeliveryJob"
+
     # Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
     # Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
     # config.time_zone = 'Central Time (US & Canada)'
Index: lib/redmine/info.rb
===================================================================
--- lib/redmine/info.rb	(revision 19478)
+++ lib/redmine/info.rb	(working copy)
@@ -16,7 +16,7 @@
           ["Rails version", Rails::VERSION::STRING],
           ["Environment", Rails.env],
           ["Database adapter", ActiveRecord::Base.connection.adapter_name],
-          ["Mailer queue", ActionMailer::DeliveryJob.queue_adapter.class.name],
+          ["Mailer queue", ActionMailer::MailDeliveryJob.queue_adapter.class.name],
           ["Mailer delivery", ActionMailer::Base.delivery_method]
         ].map {|info| "  %-30s %s" % info}.join("\n") + "\n"
 
Index: test/unit/mailer_test.rb
===================================================================
--- test/unit/mailer_test.rb	(revision 19478)
+++ test/unit/mailer_test.rb	(working copy)
@@ -968,14 +968,14 @@
   end
 
   def test_with_synched_deliveries_should_yield_with_synced_deliveries
-    ActionMailer::DeliveryJob.queue_adapter = ActiveJob::QueueAdapters::AsyncAdapter.new
+    ActionMailer::MailDeliveryJob.queue_adapter = ActiveJob::QueueAdapters::AsyncAdapter.new
 
     Mailer.with_synched_deliveries do
-      assert_kind_of ActiveJob::QueueAdapters::InlineAdapter, ActionMailer::DeliveryJob.queue_adapter
+      assert_kind_of ActiveJob::QueueAdapters::InlineAdapter, ActionMailer::MailDeliveryJob.queue_adapter
     end
-    assert_kind_of ActiveJob::QueueAdapters::AsyncAdapter, ActionMailer::DeliveryJob.queue_adapter
+    assert_kind_of ActiveJob::QueueAdapters::AsyncAdapter, ActionMailer::MailDeliveryJob.queue_adapter
   ensure
-    ActionMailer::DeliveryJob.queue_adapter = ActiveJob::QueueAdapters::InlineAdapter.new
+    ActionMailer::MailDeliveryJob.queue_adapter = ActiveJob::QueueAdapters::InlineAdapter.new
   end
 
   def test_email_addresses_should_keep_addresses