Chocolate Pi: thanks for the information. I didn't know any ISP's actually did this. As far as I know, mine doesn't, because I seem to get every virus around.

Regarding privacy, I always assume that anything I send or receive via email (or post on the internet) can be seen by others, either at the server or somewhere along the way.

Regarding spam, I guess I'd rather not have anything filtered out unless I choose that option, except for known virus signatures. Choices about filters should be made by the customer and could be implemented by the ISP.