Spammers' IP addresses can certainly be identified, although they change IP addresses often, so it becomes a constant game of whack-a-mole. High-volume spammers have numerous servers sending out spam, each with its own IP address (a computer's numeric "name" online, IP numbers correspond with server names such as "mail.yourcompany.com"). Several organizations, such as Spamhaus.org and the Real-Time Blackhole list, call out spammers by publishing lists of their IP addresses. E-mail administrators can subscribe to constant updates of the lists, in order to filter out messages sent by those machines -- anything matching a blacklisted IP address will be immediately deleted before it reaches its destination or will be otherwise quarantined. This, sadly, is the part where the spammer simply gets a new IP number and goes about his or her business making everyone miserable.

Unfortunately, when spammers change IP addresses, the old ones are recycled and assigned to new owners, who can find the numbers useless because they appear on blacklists. Just as unfair to another group of honest Web citizens, spammers -- ever on the move -- are not averse to "borrowing" an IP address from an unsuspecting machine, using a virus to hijack a user's home computer and routing spam through it. Some users may not even notice the bandwidth use or changes in system performance. Such scenarios give home computer users all the more reason to conduct a thorough overhaul of their system security.

It's not all bad news, however. Today's e-mail world is a much different one than existed even just 10 years ago. Spammers had a sort of gold-rush period in the earlier days of the Web's popularity explosion, when it was essentially an open front door into anyone's e-mail inbox. Long-time e-mail users will remember well spending inordinate amounts of time deleting spam from their inboxes. More recent years have seen a vast improvement in spam detection algorithms used by ISPs and corporate mail administrators the world over. Spammers have a much harder time today squeaking their odious messages through such filters. If your ISP provides access to it, just check your "Junk" e-mail folder from time to time to see how many messages are no longer bothering you.