Registering with ISP Feedback Loops

What is an ISP Feedback Loop? These “FBLs” are mechanisms by which ISPs send reports back to senders or sending email platforms detailing who complained about specific email messages by clicking on the “report spam” or “this is spam” button. 

ISP Feedback Loops provide valuable information back to email senders. Unsubscribing complainers is important; this means their request to have the mail stop is respected and that a sender won’t upset that subscriber further. But it’s only a start. A high level of these FBL spam reports suggests a permission, list hygiene, or subscriber expectation issue is in play. Review and correlation of this complaint data back to which sends, which lists and which content are paramount to understanding what might be going wrong with your email marketing program. After identifying what is making subscribers unhappy, you can adjust and improve what you’re doing to help make subscribers happier and more interested in your email messages, helping maximize your ability to get mail delivered to the inbox. 

A number of ISPs offer feedback loops. Some FBLs are managed directly by the ISP, and others are outsourced to a company called Validity (previously called Return Path). 

Just a few of the most common ISP Feedback Loops include: BAE Systems (, BlueTie, Comcast, Cox, Fastmail, Italia Online, LiberoMail, Virgilio,, Liberty Global, UnityMedia, Locaweb,, Microsoft, OpenSRS, Rackspace,, Synacor, Telenor, Telstra, Terra, UOL, Verizon Media Group (AOL and Yahoo), Virgin Media, XS4ALL, Yandex and Ziggo. 

Need help navigating the world of ISP Feedback Loops? 

My name is Karen Balle, and I’m an email deliverability expert. I can help with that! 

Contact me today.