There are a couple of situations where you may want your server to send email through a third party provider. A common case of this is when you run a server from home such as an Asterisk PBX for your home phone. The server is capable of sending an email when a voicemail is left. In many cases sending from a home connection will not work. As a result you may need to relay your servers email to allow delivery. In this example I will be using Postfix on Arch Linux and Zoho Mail will be the mail server I will relay through.