class ActionMailer::Parameterized::MessageDelivery

def enqueue_delivery(delivery_method, options = {})
  if processed?
    super
  else
    @mailer_class.delivery_job.set(options).perform_later(
      @mailer_class.name, @action.to_s, delivery_method.to_s, params: @params, args: @args)
  end
end

def initialize(mailer_class, action, params, ...)
  super(mailer_class, action, ...)
  @params = params
end

def processed_mailer
  @processed_mailer ||= @mailer_class.new.tap do |mailer|
    mailer.params = @params
    mailer.process @action, *@args
  end
end