class ActionMailer::Base

def process(method_name, *args) # :nodoc:
  payload = {
    mailer: self.class.name,
    action: method_name,
    args: args
  }
  ActiveSupport::Notifications.instrument("process.action_mailer", payload) do
    super
    @_message = NullMail.new unless @_mail_was_called
  end
end