Allow account-level (or per-list) configuration of "inactive" criteria, combining:

Time-based rule: Contact is marked inactive if not uploaded/added to any list within X days (customer-configurable; DJ suggested starting at 30-60 days).

Engagement-based rule: Contact is marked inactive if no click (or other defined engagement event — reply, opt-in confirmation, etc.) within Y days (DJ suggested 90 days).

Logic combination: Contact should be treated as active if EITHER condition is met (recently uploaded OR recently engaged) — inactive only if both thresholds are exceeded.

Inactive contacts should be automatically excluded from active sends/campaigns without requiring manual list management, but remain in the account (not deleted) and be eligible to re-activate if they later engage or are re-uploaded.