diff --git a/config/initializers/dolist.rb b/config/initializers/dolist.rb
index b38a97e2c..7835b532a 100644
--- a/config/initializers/dolist.rb
+++ b/config/initializers/dolist.rb
@@ -1,3 +1,5 @@
 ActiveSupport.on_load(:action_mailer) do
+  require "dolist/api_sender"
+
   ActionMailer::Base.add_delivery_method :dolist_api, Dolist::APISender
 end