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Managing the Suppression List

A Suppression List is an automated safety mechanism that prevents your application from sending emails to addresses that have previously hard-bounced, marked your mail as spam, or unsubscribed. Repeatedly attempting to send to non-existent or complaining addresses damages your IP and domain reputation, quickly causing inbox providers to route your messages to spam.

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What Triggers Automatic Suppression?

  • Hard Bounces (550 User Unknown): If a recipient mailbox does not exist or the domain is dead, the address is permanently suppressed.
  • Spam Complaints: When a recipient clicks “Report Spam” in a supported webmail client (via Feedback Loop), the address is instantly suppressed.
  • Unsubscribes: When a user opts out via your unsubscribe link or List-Unsubscribe header.

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What Happens When You Send to a Suppressed Address?

Mailofly immediately drops the message before dispatch.
  • Log Status: The email status is marked as failed or suppressed.
  • Reason Captured: Recipient address is suppressed due to previous hard bounce or complaint.
  • Billing: Suppressed drops do not count against your billable sending quota.

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Removing an Address from Suppression

If a recipient made a mistake or resolved their mailbox issue:
  1. Go to Suppressions in your dashboard.
  2. Search for the email address.
  3. Review the bounce reason and timestamp.
  4. Click Remove from Suppression to re-enable sending.