Flesh tones

Increasing numbers of companies are using technology to monitor what is inside mail messages and what employees are looking at on the web. E-mail messages are most often scrutinised to stop viruses propagating and crippling a company's internal computer network or destroying vital records. Most virus scanners work by looking for telltale chunks of computer code found in other malicious programs. But using similar filtering systems to spot pornographic images would be much more difficult, said Martyn Richards, European head of filtering firm Tumbleweed. "It takes more than just looking for flesh tones," said Mr Richards, adding that innocent images could sometimes be caught by systems set up to stop pornography.

Badly configured systems could create a lot of false positives and stop staff receiving blameless messages.

Find the filth

The sheer scale of the task facing Ford could also limit the effectiveness of its plans to stamp out smut, sexist and racist material. Joe Frost, a spokesman for search firm Inktomi, said it helped many firms catalogue the information found on their internal servers, but none so far had extended this to individual PCs. Ford currently has about 345,000 employees, meaning it will potentially have to search through billions of files for anything suspicious. Many of these files would have to be opened by drive cleaner software to confirm their contents. Employees who could be sacked for storing offensive material on their PC were unlikely to give it a filename that exactly described its contents, said Mr Frost.

The fact that many of these work computers could be laptops taken home in the evening and during the weekend could make the problem of spotting smut much more difficult. "There's no guarantee that they are going to be able to clean the offensive material out of the system quickly," said Geoff Haggart, European head of filtering firm WebSense. "It's far better to stop it happening in the first place," he said. "More and more companies are beginning to realise that this is an issue they should have been looking at before now."

Many companies use filtering software, produced by companies such as SurfControl and WebSense, which uses a watchlist of sites and stops employees reaching any website on the banned list. But, said Mr Haggart, many filtering systems are too crude and let through sites they should block and stop those that are innocent. The speed with which websites can spring up and move can also catch out some filtering systems, said Mr Haggart.