Suppression prevents existing contacts from being re-prospected. Deduplication prevents the same contact from entering multiple campaigns simultaneously.
acme.com — they are a customer)Settings → Suppression: upload CSV of domains or emails, sync CRM accounts tagged as "Customer" or "Churned" automatically, view and remove entries.
Deduplicates by email address. If the same email appears in two active campaigns, only the first enrollment is active. The duplicate is held pending until the first campaign completes.
Deduplication is per workspace, not per rep. First campaign to match the contact wins.