Your Router need to have the WAN IP set up to that same IP address. Also set up the router so it can respond to ping requests. Be sure you can ping the address and it replies.

Your ISP needs to create a DNS Pointer pointing mail.xyz.com to IP x.x.x.x

Propagation can take up to 48 hours, especially if you are also using an on-line spam filtering system such as Postini.

A great solution must not only provide backup and restore capabilities; it must be fast, reliable and simple to use.

Using a company to assist you in selecting a solution will not just eliminate the confusion of selecting the right backup. A specialized backup solution provider will set up the backup with you, monitor it for consistency and accuracy, and will perform routine restore tests.

When you do need a file or entire system recovered, you should rely on the people who set up your backup solution to help you with the process; this will reduce downtime and eliminate headaches for you.