Email feedback loops (FBLs) allow email receivers to tell a sending network about the complaints their users are generating about email originating from the sending network. By tuning in to FBL data, sending networks can identify problematic email traffic originating from their IP address space, such as spam messages. This information can help to pinpoint and then shut down spammers.
Many large email receivers provide FBLs, which you can freely register for by clicking on the links below:
- Hosted Email
- Terra (Brazil)
- United Online
Google's Gmail service also offers a feedback loop, which is currently in beta. To indicate your interest in the Gmail FBL, visit this signup form. Not all senders will be accepted into their FBL program.