Suppression list (blacklist) system

SmartRelay shares the suppression list management system that is used by Contactsend.

Unknown user/invalid recipient bounces, for example, are immediately added to a suppression list as soon as they are received and processed. For privacy reasons, each such suppression list is customer-specific.

Other bounces are managed using smart, time-based, temporary suppression logic. This adds a recipient to, or removes a recipient from, the relevant suppression list until either:

• The seven week time limit is reached, with no successful delivery
  • The recipient is added to the suppression list permanently

or:

• A successfully delivery is recorded before then end of the time limit
  • The recipient is marked as valid

This logic ensures that:

• False positives are reduced to a reasonable minimum, even for infrequently used mailboxes
• Mail service providers (MSPs) do not see many messages sent to a potentially disabled mailbox before the attempts stop permanently
  • MSPs consider this problem a symptom of bad list management practices, which has a negative impact your sender reputation