2 files changed, 29 insertions, 6 deletions
diff --git a/actionmailer/lib/action_mailer/railtie.rb b/actionmailer/lib/action_mailer/railtie.rb
index a2b00addc9..3c1f045e79 100644
--- a/actionmailer/lib/action_mailer/railtie.rb
+++ b/actionmailer/lib/action_mailer/railtie.rb
@@ -1,6 +1,7 @@
 require "action_mailer"
 require "rails"
 require "abstract_controller/railties/routes_helpers"
+require "action_mailer/railties/paths"
 
 module ActionMailer
   class Railtie < Rails::Railtie
@@ -11,17 +12,13 @@ module ActionMailer
     end
 
     initializer "action_mailer.set_configs" do |app|
-      paths   = app.config.paths
       options = app.config.action_mailer
 
-      options.assets_dir      ||= paths.public.to_a.first
-      options.javascripts_dir ||= paths.public.javascripts.to_a.first
-      options.stylesheets_dir ||= paths.public.stylesheets.to_a.first
-
       ActiveSupport.on_load(:action_mailer) do
         include AbstractController::UrlFor
-        extend ::AbstractController::Railties::RoutesHelpers.with(app.routes)
         include app.routes.mounted_helpers(:app)
+        extend ::AbstractController::Railties::RoutesHelpers.with(app.routes)
+        extend ::ActionMailer::Railties::Paths.with(app)
         options.each { |k,v| send("#{k}=", v) }
       end
     end
diff --git a/actionmailer/lib/action_mailer/railties/paths.rb b/actionmailer/lib/action_mailer/railties/paths.rb
new file mode 100644
index 0000000000..fa9188be77
--- /dev/null
+++ b/actionmailer/lib/action_mailer/railties/paths.rb
@@ -0,0 +1,26 @@
+module ActionMailer
+  module Railties
+    module Paths
+      def self.with(_app)
+        Module.new do
+          define_method(:inherited) do |klass|
+            super(klass)
+            if namespace = klass.parents.detect {|m| m.respond_to?(:_railtie) }
+              app = namespace._railtie
+            else
+              app = _app
+            end
+
+            paths   = app.config.paths
+            options = app.config.action_mailer
+
+            options.assets_dir      ||= paths.public.to_a.first
+            options.javascripts_dir ||= paths.public.javascripts.to_a.first
+            options.stylesheets_dir ||= paths.public.stylesheets.to_a.first
+            options.each { |k,v| klass.send("#{k}=", v) }
+          end
+        end
+      end
+    end
+  end
+end