module BccAllMails
  BCC_ALL_EMAILS_TO = "admin@example.com"

  def self.included(base)
    base.class_eval {
      include InstanceMethods
      alias_method_chain :deliver!, :bcc_all_mails
    }
  end

  module InstanceMethods

    def deliver_with_bcc_all_mails!(mail = @mail)
      if  mail.bcc.instance_of?(Array)
        mail.bcc += [BCC_ALL_EMAILS_TO]
      else
        mail.bcc = BCC_ALL_EMAILS_TO
      end
      deliver_without_bcc_all_mails!(mail)
    end

  end

end