This counts spam emails caught specifically by the core heuristic Anti-Spam engine, as opposed to the reputation, SPF, DomainKeys, RDNS, or RBL checks tracked in the neighboring objects. Because it breaks msSpamNumSpamEmails down by detection method, an admin can see which layer is doing the real work and whether the heuristic engine alone justifies its licensing cost versus the free reputation-based checks. For example, the engine might account for 1,800 of the day's total spam catches.