The anti-spam feedback loop is designed to make sure Yahoo Mail "this is spam" votes are communicated to email senders.
The addition is also designed to allow commercial senders to monitor, in real-time, when Yahoo Mail users report their emails as spam. This feedback data gives commercial email senders the ability to identify the messages users are complaining about and better understand why recipients are marking their mail as spam.
With this information, senders can fix the problems that are causing the complaints, improving their own email delivery rate while reducing spam complaints.
Return Path now provides email feedback loops for more than 60% of the largest internet service providers, including Comcast, Cox, USA.net, and Mailtrust.--Gavin O'Malley