What Giok said, plus the following.

My ISP allows three mailboxes with five addies on each.

I keep one box for sites that require registration, and use different addies for various types of activity.

Second box is for private use, and only friends and family get that.

Third box currently unused. I'm saving it for when box one gets to be more trouble than it's worth.

Usernames for my private addies are random numbers and letters which don't allow targetting by spammers who post randomly to blocks of names (i.e. multiple Thompsons, Thomases etc).

I don't get spam on the private box, and Spamfighter does a good job on the other.

Don T.