'ello, I have noticed scripts in the interface up/down directories in /etc that relate to Postfix. These may be of help (as I'm assuming non-fixed IP means that your connection is intermittent).
It may be convenient to get a domain name from http://www.dyndns.org/ as they supply software that automatically updates your domain name to point to your IP when you are reconnected. There are Debian packages containing such software. Hope this helps, bye just now, -- Matthew T. Atkinson <[EMAIL PROTECTED]> -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]