action_mailer.rb

ActionMailer::Base.class_eval do

  DELIVERIES_CACHE_PATH =⋅
    File.join(RAILS_ROOT,'tmp','cache','action_mailer_acceptance_deliveries.cache')

  def perform_delivery_acceptance(mail)
    deliveries << mail
    File.open(DELIVERIES_CACHE_PATH,'w') do |f| 
      Marshal.dump(deliveries, f)
    end 
  end 

  def self.cached_deliveries
    File.open(DELIVERIES_CACHE_PATH,'r') do |f| 
      Marshal.load(f)
    end 
  end 

end