diff --git a/lib/active_decorator/railtie.rb b/lib/active_decorator/railtie.rb
index <HASH>..<HASH> 100644
--- a/lib/active_decorator/railtie.rb
+++ b/lib/active_decorator/railtie.rb
@@ -13,6 +13,7 @@ module ActiveDecorator
       end
       ActiveSupport.on_load(:action_mailer) do
         require 'active_decorator/monkey/abstract_controller/rendering'
+        ActionMailer::Base.send :include, ActiveDecorator::ViewContext::Filter
       end
     end
   end
Add ViewContext::Filter include to ActionMailer::Base

When 'ActionMailer::Base' is delivered by Model or Worker(like ActiveJob),
'ActiveDecorator::ViewContext.current' is 'nil' and cannot use view helper methods in decorator.
the reason is that 'ActionMailer::Base' inherits 'AbstractController::Base',
but only ActionController::Base set view_context.