Outbound Glossary
Suppression list
The list of people and domains you must never contact. It is the one list that has to be shared across every tool you run.
A suppression list holds opt-outs, existing customers, live opportunities, competitors, and anyone a client has asked you to leave alone. It is checked before a send, not after.
Keep it at the domain level as well as the address level. A prospect who opted out from one mailbox usually does not want three of their colleagues approached either, and a client whose account team is already in conversation will not thank you for a cold email into the same building.