1. Before choosing a spam filter it is important to decide if the filtering should take place at the user’s computer or at the server level.
i. Large organizations that do not want their employees to be bothered by spam should choose for a server-side solution. The main advantage of a server-side solution is that with a good system the spam never reaches the employee. Unfortunately there are many poor server-side filters available that for example require the employees to manually search for any classification mistakes. Since indirectly that way the spam still reaches the end user, it minimizes the main advantage of a good server-side filter. Maintaining a good server-side solution in-house requires a lot of expertise and can therefore be costly. Outsourcing the spam problem to a specialized company is therefore generally more cost-effective here.
ii. Using a filter directly on the user’s computer can be beneficial because email is always locally stored and therefore full control over the email remains. Furthermore the software can learn user-specific spam recognition allowing the filtering to be custom tailored to the user. Because the need to actively check for mistakes this is still quite time intensive though making it only an interesting solution for home and small business users.
2. To decide what solution to choose it is important to ensure that it is compatible with your current infrastructure. Minimum adjustments should be necessary to avoid making the setup more complex than necessary. There is always a solution that fits your setup.
3. To keep track of what is happening, it is important that you can have direct access to all blocked messages or to a report listing all blocked messages. Although you should hardly ever need this feature, there is nothing more frustrating than not knowing what happened with your message (or what did not happen).
4. Whenever a classification mistake is made, this should be easily correctable. You should be able to release the message so it is normally delivered to your email application.
5. Test, test, test. Always test the filter for at least 2 weeks (most companies offer free trials). The antispam market is quickly getting crowded with many poor filters resulting in solutions that are more costly than the spam problem they are supposed to solve. Try to find out if you are not dealing with a reseller during the trial and always do direct business with the antispam experts themselves.
