What is a suppression list?
The list of people who never get outreach again, checked at build time and again at the moment of send.
Suppression list — A suppression list is a set of contacts, emails or domains that must never receive outreach — unsubscribes, bounces, complaints, customers, competitors, legal holds. It is applied when an audience is built and again when a message is sent.
Why it matters
A suppression list is what keeps a sending program from re-contacting people who have already said no, bounced, or complained. It typically merges several sources into one check: explicit unsubscribes, hard bounces, spam complaints, current customers, named competitors, and any contact under a legal hold.
For a sales team, the list matters most at the exact moment a message is about to send, not only when an audience is first built, because time passes between building a segment and sending to it, and a contact can unsubscribe from an earlier campaign in that gap. A team that checks suppression only once, at list-build time, will still send to someone who opted out an hour later. For an agency running outreach across several clients, each client's suppression list has to stay separate, since a contact who opted out of one client's emails has not opted out of another's. In SalesCrew, suppression is enforced both when an audience is frozen and again at send.
Where suppression gets checked
- 1
A contact takes a suppressing action
They unsubscribe, bounce hard, complain, or are added to a manual hold.
- 2
They are added to the suppression list
The event is recorded against their email, domain or record.
- 3
An audience is built for a send
A segment is filtered, and the suppression list is checked at this point.
- 4
The audience is frozen
The list is fixed for this specific send, with suppressed contacts removed.
- 5
Suppression is checked again at send
Anyone who opted out between freeze and send is caught here too.
The mistake to watch for
Questions
- How is a suppression list different from a do-not-call list?
- A do-not-call list is specific to phone outreach and is often tied to a legal registry, such as the US National DNC Registry. A suppression list is broader and channel-agnostic, covering email, domains and any other outreach a business runs, built from opt-outs, bounces, complaints and internal holds.
- Who ends up on a suppression list?
- Anyone who unsubscribed, any address that hard-bounced, anyone who marked a message as spam, current customers who should not get cold outreach, named competitors, and any contact placed under a legal or compliance hold.
- Does a suppression list need to be checked more than once per send?
- Yes. It should be checked when a segment is built, again when that segment is frozen into a fixed send list, and once more at the moment of send, since the list changes constantly between those points.