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List Management

Suppression List

A list of email addresses that are excluded from receiving emails, including unsubscribes and bounces.

Definition

A suppression list is a collection of email addresses that are blocked from receiving your emails. It includes unsubscribes, hard bounces, spam complainers, and manually excluded addresses. Suppression lists are critical for compliance and deliverability, ensuring you do not send to people who should not receive your emails.

Why It Matters

Sending to suppressed addresses violates regulations (sending after unsubscribe), damages sender reputation (sending to complainers), or wastes resources (sending to invalid addresses). Properly maintained suppression lists protect your deliverability and legal compliance.

How It Works

Your ESP automatically adds addresses to suppression lists when they unsubscribe, bounce, or complain. You can also manually add addresses. Before each send, the system checks against suppression lists and excludes matching addresses. Suppression lists should persist even if addresses are re-imported.

Best Practices

  • 1Never remove addresses from suppression lists without a legitimate re-opt-in
  • 2Maintain suppression lists across all sending platforms
  • 3Check suppression reasons when investigating deliverability issues
  • 4Merge suppression lists when consolidating ESPs or lists

Frequently Asked Questions

Only with a new legitimate opt-in. Never remove unsubscribes just to email them again. Hard bounces should stay suppressed unless you verify the address is now valid. Removing complainers risks your reputation.

Unsubscribe list is one component of suppression. Suppression lists include unsubscribes plus hard bounces, spam complaints, and any manually excluded addresses. All should be excluded from sends.