How to fetch "Reply-To" attribute from email by using mailman (Rails)?

I am polling emails from my rails application by using Mailman gem. I followed the Railcasts here

In that Railscasts, Ryan Bates showed how to retrieve the Subject and the Content from the email that we received, and I could follow that just fine.

But now, I want to fetch the other attribute from the email, more specifically the "Reply-To" attribute. So how could I do this?

I have tried to do this like this: message.Reply-to, but I got

undefined method `Reply' for #<Mail::Message:0x007fc0fd641890> (NoMethodError) 

when I tried to test it. Below is the screenshot of the full error message:

Below is my mailman_server file:

#!/usr/bin/env ruby
require "rubygems"
require "bundler/setup"
require "mailman"

#Mailman.config.logger = Logger.new("log/mailman.log")

Mailman.config.pop3 = {
  server: 'pop.gmail.com', port: 995, ssl: true,
  username: "xxxxx@gmail.com",
  password: "xxxxx"
}

Mailman::Application.run do
  default do
    puts "Received: #{message.Reply-To}"
  end
end

Below is my mailman_test.eml file:

Date: Fri, 25 February 2016
From: myappsender@gmail.com
Subject: Mailman Test
To: myappsupport@gmail.com
Reply-To: myappreply@gmail.com

mailman gem internally uses Mail::Message while processing the incoming mail.

So you have access to all the methods of Mail::Message at your disposal. One of those methods is reply_to. So you could try message.reply_to.

Refer to Mail::Message Documentation for more info.