A free tool for fighting spam. Bloomberg Boot Camp, a report on today's technology. The battle continues against the flood of unwanted email. Giants such as Microsoft and AOL have filed lawsuits and have improved spam filters. Lawmakers vow to legislate an end to the problem. But the efforts so far…have barely made a dent in the annoying and sometimes offensive email just about everyone who is online is inundated with. Now a company called DigiPortal is offering a free version of its ChoiceMail software to consumers. Founder and chief technology officer David Jameson…says the software isn't just another filter…

"ChoiceMail is essentially a challenge-response system. The idea is like somebody coming to your front door. If you don't know who they are, they need to knock, they don't have the right to just come in. So in our system, if you send me a message and I don't know who you are, or more correctly my system doesn't know who you are, it will send a message back to you basically asking you who are you…and you have to respond."

It virtually eliminates automated spam…and other nuisance email. Jameson argues it's a better solution than software that filters…

"the problem with passive filtering systems is it's really quite easy for spammers to get around them. In fact, you end up in an escalating battle all the time."

The free version of ChoiceMail….from DigiPortal.com…will work with a single pop email account. A version that will work with services like Hotmail and AOL, costs 40 dollars. Bloomberg Boot Camp, I'm Fred Fishkin.