Backscatterer blacklist


The Backscatterer blacklist includes IP addresses that send misdirected bounces or auto-response messages to forged sender email addresses. These bounces or auto-response messages may be sent to Return-path, From or Reply-to domains that were forged as the sender of spam messages.

Bounce backscatter is caused when the receiving server accepts a message for delivery but later determines that the message cannot be delivered. The receiving server then sends a bounce message back to the forged sender address indicating non-delivery.

Auto-response backscatter is caused by sending notification emails such as out-of-office messages or other notifications to the forged sender address.

How your server handles these types of bounces can cause all sorts of problems, especially if your server is hit with a directory-harvesting attack.

  • Backscatterer listings occur at the IP address level.
  • The impact on deliverability is minimal.

Reasons for getting listed

IP addresses are listed for:

  • Sending misdirected bounced messages or auto-response messages to spam traps owned by the blacklist

How to get off this blacklist 

IP addresses are listed for four weeks and then removed if you fixed the underlying problem. You can also ask Backscatterer to remove your IP address by paying a fee. Keep in mind, however, that asking to be removed and paying the fee without correcting the issue is a short-term solution and is not recommended.

Tips for staying off this list

  • Check your server configuration and turn off auto-replies
    • Only send out-of-office messages to internal users if your system supports it
  • Review your mail server configuration to determine how the rejection of incoming email is handled so you can minimize the risk of sending backscatter
    • Ensure that it is handling bounces synchronously, which means that rejections (bounces) occur immediately during the SMTP conversation, rather than after the email has been accepted by your server


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