diff --git a/config/initializers/10-patches.rb b/config/initializers/10-patches.rb
index aa51c0e7a..f409f6611 100644
--- a/config/initializers/10-patches.rb
+++ b/config/initializers/10-patches.rb
@@ -65,9 +65,9 @@ end
 
 ActionView::Base.field_error_proc = Proc.new{ |html_tag, instance| "#{html_tag}" }
 
-# Adds :async_smtp and :async_sendmail delivery methods
-# to perform email deliveries asynchronously
 module AsynchronousMailer
+  # Adds :async_smtp and :async_sendmail delivery methods
+  # to perform email deliveries asynchronously
   %w(smtp sendmail).each do |type|
     define_method("perform_delivery_async_#{type}") do |mail|
       Thread.start do
@@ -75,6 +75,13 @@ module AsynchronousMailer
       end
     end
   end
+
+  # Adds a delivery method that writes emails in tmp/emails for testing purpose
+  def perform_delivery_tmp_file(mail)
+    dest_dir = File.join(Rails.root, 'tmp', 'emails')
+    Dir.mkdir(dest_dir) unless File.directory?(dest_dir)
+    File.open(File.join(dest_dir, mail.message_id.gsub(/[<>]/, '') + '.eml'), 'wb') {|f| f.write(mail.encoded) }
+  end
 end
 
 ActionMailer::Base.send :include, AsynchronousMailer