Fish,
Once your email acount is out there and known, there's not a lot you can do to 'stop spam' other than change you email address on a fairly regular basis, but this may not be an option.
You can install a spam checker (I use Spam Inspector which is pretty good), which with a bit of training will move most of the spam to the bin before you get to see it. This is the option I would go for as it will filter your mail and do a pretty reasonable job. A fair number of spam filters give the option to 'bounce' the email back from whence it came, making the sender look like the email address no longer exists. This is a fairly pointless exercise (although it feels good!) as the address is rarely the true sender. My own email address has been used to send spam/virus'.
As a further piece of advice, I would look to move off outlook/outlook express. Every virus writer knows where outlook stores it's address book, and what format it is in. As a consequence, the majority of virus' that can be spread be email utilise this program. Try something else instead. I use Incredimail which is free and much more fun that Outlook.
Hope this helps.
Marc
The only real option, as mentioned by micker377 is to change
