Re: Static IP
 

Not all Virgin customers have internet.

There are a few ISPs that will dish out static IPs for no charge, such as PlusNet.

Re: Static IP
 

Private eMail servers like Exchange or Postfix must be setup with a static IP in order to work with pulic mail providers such as Google, Yahoo, Hotmail etc.
The reported errors are usually something like "invalid reverse DNS pointer". The solution is a static IP, dyndns won't work.

Re: Static IP
 

or configure a relay host.

relayhost=smtp.virginmedia.com

in main.cf if using postfix.

Of course, could be a pain for incoming email. IME the IP changes so rarely though. It may be worth setting a low ttl on the DNS entry for the hostname that you use for your mx.