The purpose of this tutorial is to assist you in understanding what MX (mail exchange) records are, and the role they play in your life.

An MX record tells senders how to send email for your domain. When your domin is registered, it is assigned several DNS records. This enables it to be located on the Internet in several different ways. Every MX record points to an email server that is configured to process mail for that domain. Typically, one record points to a primary server, and additional records point to one or more backup servers. For users to send and receive email, the MX record for their domain must point to a server that can process their mail. This allows your mail to travel freely back and forth, arriving at the correct inbox.

Mx records are typically set up first with a priority. This priority can range from 0 to 99, with the lower the priority number, the more priority is given to that mail server.
Mail servers are normally named after the domain they serve with and follow general server naming conventions such as:
mail.YOURdomain.COM
pop3.YOURdomain.COM
smtp.YOURdomain.COM
imap.YOURdomain.COM
or anything set forth by your host, so check with them you you are not sure.

You can even have multiple MX records to handle incoming and outgoing mail, or as backup on another server etc.

This concludes this tutorial. You are now familiar with the workings of Mail Exchange (MX) records and the role it has in your hosting.