MIME sweeper SMTP Appliance CS500 2.4 review

For a number of years, Clearswift concentrated on providing message security software. But the company gave in to the allure of the appliance last year, with the result that its CS500 has been sitting pretty on the A List ever since. And for good reason too, as it delivers an unbeatable range of features at a sensible price.

Clearswift recently updated the appliance’s Linux kernel and here we take a look at the new features in more detail. Four appliances make up the family and the CS500 targets SMBs with up to 500 employees. Hardware options haven’t changed much, though. The system supplied has the same hardware as its predecessor, although Clearswift advised us that Celeron versions are now available. The choice of platform is better than a lot of the competition, as the CS500 uses a well-built and exceedingly quiet Dell PowerEdge 850.

Basic high availability is supported. You can place multiple appliances on the network to provide failover, although all you do is create DNS MX records for each one and assign them different priorities. If the primary appliance fails, the company mail server will just use the secondary appliance. A new feature for multiple systems is peer grouping, where you join appliances into a group using their IP addresses. Policies can then be replicated automatically to all systems in the peer group, synchronising them.

Clearswift’s anti-spam measures have always been tough, but they get beefed up even more with the addition of another service. This comes courtesy of Mail-Filters, which specialises in OEM solutions and functions as an extension of Clearswift’s SpamLogic service. Configuring anti-spam measures has also got even easier, as you use a new slider bar in the web interface to determine how aggressive the spam filters should be. You may wish for spam to be blocked if only one of the engines detects it, or be more lenient and only block the message if two or three of them flag it as spam. The CS500 also employs features such as Bayesian analysis with auto-learning, URL categorisation engines, Clearswift’s own managed spam signature list and RBLs, but all can be configured easily in a matter of seconds.

Rules for handling spam or infected messages have also been improved and offer a secondary action. For example, you can now deliver a message to its recipient and send a copy to a third-party archiving server. Another rule could have a primary action of blocking a suspect message from being delivered to a recipient or sent from an employee, but having a copy sent to a manager. Reporting is another impressive feature. A raft of predefined reports are provided, which can be scheduled to run at regular intervals and the output emailed to selected users.

Apart from the extra features, the web management interface hasn’t changed much. But it doesn’t need to, as it’s still one of the best designed and most intuitive around. Every function is easily accessible and it provides a full range of tools for dealing with messaging security and enforcing AUPs in the workplace. We’ve yet to see anything at this level to challenge the CS500 for ease of use, value and features.