Definition
List hygiene includes: removing hard bounces immediately, suppressing subscribers with zero opens in 90 days (or running re-engagement campaigns first), validating new signups against verification services like ZeroBounce or NeverBounce, removing role-based addresses (info@, admin@) where appropriate, and respecting unsubscribes. A clean 3,000-subscriber list outperforms a stale 30,000 list.