Clearswift's MIMEsweeper for Web applies the company's email filtering system to the internet. It will install on a single Windows 2000/2003 server and works as a web proxy, scanning all requests.

There's a long and tedious list of items to install, including Microsoft's Messaging Queue, IIS and an update to .NET. This can be a problem if you're installing on an older server, so we recommend a fresh OS install.

Filtering web traffic is comprehensive and there's support for a wide variety of tools. But, to configure it using the MMC snap-in takes some time, as there's a steep learning curve involved.

Security policies are based on a series of detection algorithms. These classify the traffic, then the chosen classification routine chooses the action to take. It means that you can get the software working the exactly the way you want, but there's a lot of work to do out of the box.

Detection of traffic is first based on user authentication, so you can ensure that a user is allowed to access the internet. Next, you can decide which websites to block. MIMEsweeper has its own URL database, which you can configure to update on a daily basis. The database has the usual range of categories, so you can block those websites that aren't appropriate for work. Strangely, it's one of the least prominent parts of the software, hidden away under a tab in a dialogue box. It works well enough, though, and the default settings blocked all our test requests and prevented our HTTP-Tunnel connection. You can also build custom URL lists.

Next, MIMEsweeper supports Platform for Internet Content Selection (PICS). For websites that voluntarily rate themselves correctly you can block the websites but, in practice, a lot don't.

There's also a file manager, which detects and blocks file types that you don't want coming into your company. The scanner analyzes the content of the file, so changing file extensions will not fool it.

The level of protection on offer is extremely good and, given enough time, you can enforce even the most complex of policies. This more than makes up for what is a slightly difficult program to configure.