THE FIGHT against spam has hotted up, with Microsoft, the software giant, and Amazon, the online retailer, teaming up to file lawsuits against spammers.

Every day tens of millions of unsolicited e-mails selling pills, loans, pornography and even pleas for people to join in prayer are sent to computer users around the globe. The recipients have to spend time unclogging their inboxes and this stops them from doing productive work.

Large companies may have well-staffed IT departments to deal with spam, but smaller firms often find it distracting and time-consuming.

Happily, help is on the way. A company called Postini provides a spam-filtering service for small and medium-sized businesses.

Perimeter Manager is a service that will filter all e-mails before they reach a company’s network.

When a business has signed up, it will receive instructions on how to redirect its mail through Postini, and the service is then activated.

Suspect messages are held in a quarantined area away from any servers. Users get a quarantine summary from which they can select any messages that have been wrongly blocked.

Other features include a seven-day recovery facility so that if a server crashes, messages received when it is down are stored and delivered when the server becomes available.

Phil Waller, systems and network security manager for Worth Global Style Network, a fashion market-research firm, has been using the service for four months and has noticed a benefit. “I estimate the reduction in spam due to Postini to be about 98%. It’s one of the best things we have implemented at the company,” he said.

Postini has big companies such as Merrill Lynch among its clients but the Small Business Edition is set up with a “one-size-fits-all” specification designed to make its operation as unobtrusive as possible to smaller firms.

Although the simplified settings inevitably mean that users will have less control over the flexibility of the filter, they can still check what messages have been blocked and release them from the quarantined area as desired, with the further option of adding certain addresses to a “safe list”, as with Hotmail.