Definition
A suppression list is a database of email addresses that are excluded from all future sends. It is separate from your active subscriber list and should be checked before every campaign. Proper suppression list management is essential for legal compliance and deliverability.
Types of Suppressions
- Unsubscribes: Recipients who have opted out — legally required to suppress permanently
- Hard bounces: Invalid or non-existent addresses — should be suppressed after 1-2 bounces
- Spam complainers: Addresses that have marked mail as spam via FBL — must be suppressed immediately
- Litigators: Addresses known to file complaints or lawsuits
- Role-based addresses: admin@, abuse@, postmaster@ (should never receive marketing email)
- Competitors: Known competitor email addresses (optional but common)
Best Practices
Maintain a single master suppression list across all sending platforms. Check every list against the suppression list before importing or sending. Never remove addresses from the suppression list unless they explicitly re-subscribe with fresh consent.
Related Glossary Terms
AOL Mail for Email Marketers
AOL Mail is a legacy email provider with specific deliverability requirements and rendering quirks, now operating as part of the Yahoo+AOL network under shared infrastructure.
BIMI
BIMI (Brand Indicators for Message Identification) is an email standard that allows brands to display their logo next to their emails in supported email clients. It requires DMARC enforcement at quarantine or reject policy.
Bounce Rate Threshold
A bounce rate threshold is the percentage of hard or soft bounces at which email platforms and ISPs begin to penalise sender reputation, typically around 2-5%.
Bounce Rate
Email bounce rate is the percentage of emails that were rejected by the receiving server before reaching the recipient. It is a key indicator of list health and data quality.
CAN-SPAM Act
The CAN-SPAM Act is a US law that sets rules for commercial email. It requires accurate subject lines, a physical address, a clear opt-out mechanism, and prompt processing of unsubscribes. Violations can result in penalties up to $51,744 per email.
Consent Expiry (Email Marketing)
Consent expiry is the time period after which a subscriber's permission to send marketing emails legally expires and must be re-obtained, varying by jurisdiction and consent type.