If you never needed to purchase spam filtering services before, some of the names and service descriptions can be quite cryptic. Here is a very quick guide that describes the typical use cases that people have and the product that may work best in these circumstances.
If you have a mail server that you want spam filtering for, the Email Gateway product is what you need –
If you have a mail server that ALREADY has spam filtering, but you want it backed up if it goes down, take a look at the Backup MX service.
If you have a DOMAIN, and NO mail server but want mail forwarded to another account. Then the email forwarding service may solve your problems.
If you have a mail server or a desktop email client and are having problems SENDING mail to the Internet from the server. You’ll want to use our Outbound SMTP service.
I hope this information helps to clarify the services and what they do. If not please feel free to contact our support department.