While external filtering programs can be used by anyone with the knowledge and patience to set them up so that they work well, the later versions of Mozilla and Netscape, which used the same guts as Mozilla, include mail filtering tools which reject mail from senders not in your address book, as well as mail that you note as junk - they learn as you both go along. These are probably easier for the newer or less sophisticated user to set up and use than external filters. With Netscape now owned by AOL, I would expect much less growth in neat features, as compared to Mozilla which is independently owned.

Dave