X Ways Trace
doesn't claim to access email. Does this person have access to your computer?
Look on the back of the tower. Are there any hardware items in between the case and the ethernet cable? Anything that looks like an adapter but isn't needed? Some require a key to remove. See anything like that?
Go into Admin Services and disable everything that says "remote assistance". Call your ISP and change the email password (the one Outlook Express uses to get mail from your mailserver) You are running a firewall, correct? Is your computer part of a network or on a router? Do you know how to lock it down? Does ex have a laptop?
Trying to help,