What’s the difference between hard filtering and adaptive filtering?

Hard filtering applies deterministic rules:

Block messages from specific IPs. Reject messages containing certain phrases. Require specific authentication. These rules are explicit and consistent.

Adaptive filtering uses machine learning:

Learn from user actions. Adjust weights based on outcomes. Evolve as spam tactics change. Personalize decisions per recipient.

Modern providers use both. Hard rules handle known threats. Adaptive systems handle everything else and continuously improve.

Hard filtering is the rulebook at the port gate. Adaptive filtering is the experienced inspector who has seen every smuggling trick and keeps learning new ones.