class Rails::MailersController

def download
  @email_action = File.basename(params[:path])
  if @preview.email_exists?(@email_action)
    @email = @preview.call(@email_action, params)
    send_data @email.to_s, filename: "#{@email_action}.eml"
  else
    raise AbstractController::ActionNotFound, "Email '#{@email_action}' not found in #{@preview.name}"
  end
end