Feedback Loops Are Handled by PowerMTA

ISPs use three formats to report user complaints based on when a user clicks the “Spam” or “Junk” button, back to the sender of the message. Once upon a time, a good bit of human intervention was required to help the sender keep their database clean of subscribers who no longer want to receive the sender’s mail.

PowerMTA server software handles this function internally. Port25 provides this list of currently available feedback loops and how they are applied by major ISPs. You may wish to set an alert for this page.

1
Traditional (IP-Based) FBL

2
Aggregated FBL

3
Domain-Based FBL

This format, outlined in RFC 6449, is the standard used by ISPs to report user complaints back to the sender. It is based on the sending IP and reports are sent in the Abuse Reporting Format (ARF), which provides the sender with the full message and user who complained about it.

Aggregate FBL format does not provide the sender with the full message, and does not identify the user. It is an alternative to the traditional IP-based, ARF reports, which rolls up aggregate counts of complaints by IP, domain, or an identifier determined by the sender.

This format is based on the sending domain and senders must sign their mail with DKIM in order to participate in the program and determine the sending domain (d= value in DKIM signature) and the selector (the s= value in DKIM signature).

  • AOL
  • Bluetie/Excite
  • Comcast
  • Cox
  • Earthlink
  • Fastmail
  • OpenSRS/Tucows
  • Outlook.com
  • QQ.com
  • Rackspace
  • RoadRunner/Time Warner Cable
  • Synacor
  • Terra
  • USA.NET
  • United Online/Juno/Netzero
  • Zoho.com
  • Terra
  • Gmail
  • Mail.ru
  • Outlook.com
  • Cox
  • Signal Spam
  • Yahoo!
  • Mail.ru

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