SpamGunner is a anti-spam tool for POP accounts. SpamGunner includes a comprehensive set of filters that are updated and a pretty frequent basis. A nice feature is that the filters are automatically updated. Some drawbacks to SpamGunner is that you can only use it with POP accounts only and the filter is not quite as precise as some other ant-spam software.
Some features that SpamGunner has is that it checks periodically for spam and filters for multiple POP accounts. Detected spam will either be flagged or deleted immediately depending on how your filters are setup. Mail is easy to read through the interface and gives you fast access to recovering any mail that may have turned up as false spam. The filter support is great in that it lets you filter using wildcards or even by countries. You also gives you the ability to send a complaint to the sender or bounce the mail back. One of the better features of the program is the ability to create a filter from a existing message.
The downside of SpamGunner is that without using and type of statistical data the filters can be inaccurate at times and not kill all spam. This can cause the problem of spam still making it into your inbox.
SpamGunner last update is version 2.0 and costs $24.95.