SpamAssassin, popular open source spam-filtering software, will have deadlier aim thanks to an add-on tool that is being offered free of charge to small businesses and individuals by MailChannels.

The tool -- called Traffic Control 3 -- is an e-mail traffic-shaping package that slows down the transmission of spam into corporate e-mail systems. MailChannels officials say Traffic Control 3 will reduce spam volumes by 50 to 75 percent for SpamAssassin users.

``Our technology is a software package that slows down spam from suspicious sources like spam bots,'' says Ken Simpson, CEO of MailChannels. ``Our research shows that 90 percent of spammers will give up before delivering spam if the data rate of the connection is slowed down.''

With less spam entering their networks, companies will need fewer mail servers to process or store e-mail for their end users.

MailChannels has sold Traffic Control 3 to enterprise customers such as Pacific Gas & Electric, Cornell University and Wyeth for two years. Now MailChannels is offering a low-end version of its software to small businesses and individuals that use SpamAssassin.

Traffic control 3 for SpamAssassin is available here.

``E-mail traffic shaping is a technique used by many of the world's largest e-mail receivers,'' Simpson said. ``We're trying to make this technology available to everyone.''

More than 150,000 Web sites use SpamAssassin to filter their e-mail traffic, Simpson says.

``SpamAssassin supports hundreds of millions of users. But SpamAssassin is limited because it is just a content filter,'' he adds.

Simpson says MailChannels is giving the open source community access to its Traffic Control 3 software to spread the word of how well the software works and to get feedback from users.

``We know our stuff works, but the only way we have to show that was to put it out there,'' Simpson says. ``When you feed the open source community, the investment comes back and pays dividends.''

One customer very pleased with Traffic Control 3 is AlaWeb Pioneer Services, a small, rural ISP that operates in Alabama and Florida. AlaWeb supports 10,000 mailboxes and several hundred domains using Sendmail as its mail transfer agent software.

AlaWeb began using MailChannel's Traffic Control software in front of Sendmail to filter all of its incoming mail in 2005 when its spam volume went through the roof.

``Yesterday, we got 7.5 million spam, of which we filtered over 99 percent,'' says Hugh Messenger, senior network administrator for AlaWeb. ``Traffic Control inserts itself between the heavy-lifting, mail-processing software and the client trying to contact you. It weeds out a huge amount of the spam with very simple, very quick techniques, the primary one being that it throttles down the speed of the connection. . . . Within 15 to 20 seconds, about 90% of the real spammerswill have disconnected and gone away. Just the simple act of tar-pitting gets rid of a huge amount of spam in a very small, lightweight process.''

Messenger says Traffic Control helps him reduce the number of mail servers he needs to support his customers.

``Before MailChannels, when I was just running Sendmail, I could support tops about 100 inbound connections per machine. Since I put in Traffic Control, I can support 2,500 to 3,000 connections,'' he says. ``I don't even know how many machines I'd need if I didn't have MailChannels.''