Daily query counts for e-mail messages sent from a number of IP addresses having unknown reputations are collected and logged, and optionally plotted. The logged query count data may optionally be normalized. The normalized query count data may also be plotted. The normalized data is divided into regions (numerically or graphically). Next, the divided regions are tagged (symbolically or graphically) with unique, symbolic identifiers such as letters, numbers, symbols or colors. Patterns for each unknown IP address are formed based upon the tagged regions. Common good and bad patterns are also identified for known good and bad IP addresses. The reputation of these unknown IP addresses are then predicted using these identified good and bad patterns using a suffix tree (for example). Finally, an output identifying the determined reputations of these unknown IP addresses is generated and output.