Your computer dings like a slot machine with incoming e-mails, but what to do with them all? “I’ve got tens of thousands. I don’t throw anything out but spam,” says Wall Street Journal personal-technology columnist Walter Mossberg. Web-based e-mail programs limit online storage space, so Mossberg uses non–Web-based Outlook Express, which, like .Mac Mail, lets him set up automatic-filing rules that send incoming mail straight to appropriate folders. (Some Web-based programs also let you choose off-line storage, like AOL’s “filing cabinet.”) He backs up his e-mails nightly on an external drive. “Forget printing them out,” he advises. “Usually that just adds to the clutter,” agrees Peggy Duncan, the author of Conquer Email Overload With Better Habits, Etiquette, and Outlook Tips and Tricks (PSC Press, $25 at www.amazon.com). If you want to winnow, she says, ask yourself these questions: “Am I really going to refer to this again? Is there a legal reason to keep this? Is this the only place I can get the information?” If yes, then print before deleting, just to be safe.