Running your own email server can grant the owner a significant amount of freedom and experience.  It allows you to set up and maintain multiple email accounts and domains with ease and allows for keeping unwanted mail out of your inboxes.

Also, you can create email distribution lists to allow for simple delivery of messages to a predefined list of addresses, or have an unlimited (up to your hard drive size) amount of space to store mail. You also have full control over what types of spam control, virus protection and relay black lists are protecting you email server. You can also determine what types of protocols users can access their email with.

In this article I will assume you are running an email server on a direct Internet broadband connection with a single WAN IP address. I will assume that you have a server set up and understand the basis behind port forwarding and basic networking skills.

DNS Considerations
In order for other email servers on the Internet to know where to deliver mail for your domain, you must make certain entries in your DNS servers. The most important of these is the MX record. The MX records tell the names or IP addresses of the servers that are allowed to handle email for you domain. You can have multiple records of this type as each one must be assigned a weight or authority that determines the order in which each is contacted to receive mail.