Somewhere along the line, your e-mail In box started to look like your real mailbox, full of unwanted ads and "free" offers that somehow aren't. New spam- filtering software may have helped cut back on the lewdness, but those programs sometimes drop good friends in the junk folder. DigiPortal's ChoiceMail ($40 at digiportal.com; a scaled-down free version is also available) gets around that problem by checking IDs at the door to your In box. If the message is from someone already in your address book, the mail goes through, but if it's from an unknown sender, ChoiceMail sends out a challenge message. Spammers, as a rule, don't respond, but that long-lost friend you caught up with at a recent wedding probably will. You can create a separate mailbox to receive email notices from online stores; if spammers get hold of that mailbox (and they eventually will), you can simply trash it and make a new one. This lets you register for ecommerce sites without broadcasting your personal address. If only you could do that with your real-world mailbox.