// Glossary
Suppression List
A list of contacts you must never send to, including unsubscribes, complaints, and DNC numbers.
Definition
A suppression list is the set of email addresses or phone numbers that must be excluded from all sends, regardless of campaign. It includes people who unsubscribed, filed spam complaints, hard-bounced, or registered on Do-Not-Call lists. Checking every send against suppression is a legal and reputational safeguard: it prevents contacting people who opted out and protects sender reputation and deliverability.