class Rails::Generators::MailboxGenerator

def create_mailbox_file
  template "mailbox.rb", File.join("app/mailboxes", class_path, "#{file_name}_mailbox.rb")
  in_root do
    if behavior == :invoke && !File.exist?(application_mailbox_file_name)
      template "application_mailbox.rb", application_mailbox_file_name
    end
  end
end