What is an email suppression list and why does it matter?
A suppression list is the set of addresses a sender must never email again — hard bounces, spam complaints, and unsubscribes. It matters because mailing a suppressed address is the fastest route to a blocklisted domain. AeroCampaign keeps one account-level list shared across SendGrid and Amazon SES, enforced as a database anti-join at send time rather than in application memory.
- Hard bounces suppress permanently.
- Three soft bounces within 30 days escalate to a 90-day suppression.
- Spam complaints suppress permanently and cannot be removed through the UI or API.
- Unsubscribes, including RFC 8058 one-click, suppress permanently.
- Existing suppressions are imported from SES and SendGrid on connect.
- New bounce and complaint suppressions are mirrored back to AWS so the lists never drift.
The common failure is having several suppression lists — one per tool — and no single authority. A contact unsubscribes from a marketing send and then receives an outbound sequence a week later, because the two systems never spoke.
Complaint suppressions are deliberately immutable here. Resending to someone who marked you as spam is how domains get blocklisted, so the product refuses the action rather than warning about it. Every other removal is audit-logged.