# What is suppression list? Definition and examples · Leadraft

URL: https://leadraft.co/glossary/suppression-list
Summary: A suppression list is a list of addresses or domains you must never email again, such as opt-outs, hard bounces and complaints, checked before every send.

Glossary · Compliance · Last updated October 31, 2026

# Suppression list

A suppression list is a list of addresses or domains you must never email again, such as opt-outs, hard bounces and complaints, checked before every send.

**Also called:** Do-not-contact list, Do-not-email list, Blocklist (sender side).

A suppression list protects two things: the law and your reputation. CAN-SPAM requires honoring opt-outs within 10 business days; CASL requires unsubscribes to take effect within 10 business days; Yahoo asks bulk senders to honor unsubscribes within 2 days. Hard bounces and spam complaints belong on the list too, because sending to them again damages your sender reputation.

The list only works if it's applied everywhere. A common failure is suppressing an address in one campaign or one tool while it stays live in another, or rebuilding a list from scratch and re-importing everyone who opted out last quarter.

Agencies have an extra problem: one business may be a prospect for several clients. Agree in writing who owns opt-outs, and decide whether an opt-out from one client's campaign suppresses that business for every client. For local markets, where you'll email the same towns again, a shared list saves real trouble.

Suppress at the domain level when a business asks not to be contacted at all, not just the single address that replied.

## Example

A plumber replies "remove me." The agency adds the address and the domain `joesplumbing.com` to its shared suppression list, so next quarter's rebuilt Austin list skips the business automatically.

## In Leadraft

Your do-not-contact list is applied to every export and push automatically, and Instantly bounce feedback flows back from pushed leads.

## Sources

1.  1.[FTC, CAN-SPAM Act: A Compliance Guide for Business](https://www.ftc.gov/business-guidance/resources/can-spam-act-compliance-guide-business)
2.  2.[Justice Laws Website, Canada's Anti-Spam Legislation (sections 10 and 11)](https://laws-lois.justice.gc.ca/eng/acts/E-1.6/page-2.html)
3.  3.[Yahoo, Sender best practices](https://senders.yahooinc.com/best-practices/)

## Related terms

-   [CAN-SPAM ActThe CAN-SPAM Act is the US law for commercial email; it allows cold email without consent but requires honest headers, an address and a working opt-out.](https://leadraft.co/glossary/can-spam)
-   [Hard bounceA hard bounce is a permanent delivery failure, such as an address that doesn't exist, returned with an SMTP reply code starting with 5.](https://leadraft.co/glossary/hard-bounce)
-   [CASLCASL is Canada's Anti-Spam Legislation, which requires consent before most commercial emails, including implied consent for published business addresses.](https://leadraft.co/glossary/casl)
-   [Sender reputationSender reputation is the trust mailbox providers place in your sending domain and IP, built from complaints, bounces, authentication and engagement.](https://leadraft.co/glossary/sender-reputation)
-   [DeduplicationDeduplication is finding and merging records that describe the same business or person, so each appears once in a list.](https://leadraft.co/glossary/deduplication)

## Further reading

-   [Cold email laws for B2B](https://leadraft.co/blog/cold-email-laws)
-   [Integrations](https://leadraft.co/product/integrations)
-   [Opt out of Leadraft data](https://leadraft.co/opt-out)

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Last built: 2026-11-09