CAFE (Collaborative Agents for Filtering E-mails) is a multi-agent system to collaboratively filter spam from users? mail stream. CAFE associates a proxy agent with each user, and this agent represents a sort of interface between the user?s e-mail client (i.e. Microsoft Outlook, Eudora, etc.) and the e-mail server. With the support of other types of agents, the proxy agent makes a classification of new messages into three categories: ham (good messages), spam and spam-presumed. The system analyzes every single email using essentially three kinds of approach: a first approach based on the usage of an hash function, a static approach using DNSBL (DNS-based Black Lists) databases and a dynamic approach based on a Bayesian algorithm.