One of the problems with filtering "junk Email" or "spam" is a very human issue. People have remarkably different opinions, desired and needs, and therefore have different perceptions of what is junk mail and what is desirable. Even Paul Judge, original Chair of the Internet Engineering Task Force (IETF) Anti-Spam Research Group (ASRG), said, "The definition of spam is highly subjective."

Monolithic Systems
Most centralized Email filtering systems on the market today take a monolithic approach to filtering junk mail. They scrutinize the individual Email message without considering the person receiving it. All Email is treated equally by such systems without giving the recipient the opportunity to influence the decision making process. Those systems that do accept user input apply that input to all users, still without considering the individual.

Decentralized Systems
Other systems exist that operate entirely on the individual user's perceptions. These decentralized systems have little or no preconceived notion of what is or is not junk mail; they must be entirely "trained" by the user. Though these systems are very effective they are difficult to use as they must be constantly trained and are entirely useless during the initial training period. Though most people will agree on what constitutes junk mail 80% of the time each user has to train the system them self for that 80%.

Another problem with decentralized junk mail filtering is management and deployment. An IT department must install the filtering system on each end-user's desktop system and must then educate each user, making Total Cost of Ownership high. Furthermore, these desktop installations only filter Email read on that computer and not Email read from the user's home system, laptop or via web interface from the road. Finally the mail server, WAN links and LAN must bear the burden of transporting and storing each junk mail message until the filter captures it. Server-based filtering systems are the only cost effective solution for large-scale deployments.

The PUREmail Approach
Enter PUREmail. The PUREmail system is unique in that not only does it identify junk mail, but it also allows individual users the freedom and flexibility to choose without being burdened with excessive training efforts.

The PUREmail methodology is as simple as it is effective: Email messages are classified by category and sub-category. Once categorized the individual user may then choose which categories and sub-categories they want delivered to their mailbox and which should be discarded. A user's preferences can be established with a remarkable degree of granularity in less than three minutes with little or no instruction.

One of the benefits of such a system for corporate deployments is the establishment of policies and default preferences. The company can decide at the management level that certain categories are not to be received by anyone in the interest or protecting employees from harassment, while other categories may be relevant to the business on the whole. These policies override the preferences of the individual user, though each user still has control over their preferences within those policies. Management can also choose the set of preferences that all users are given by default, saving the user time and trouble.