Feedback Loop (FBL)
A Feedback Loop (FBL) is a service offered by major mailbox providers (Gmail, Yahoo, Outlook, Comcast) that sends notifications to senders when recipients mark their emails as spam. These notifications allow senders to immediately suppress complaining addresses, preventing further damage to sender reputation.
How FBLs Work
- ●Recipient clicks "Mark as Spam" in their email client
- ●Mailbox provider sends an abuse report to the sender via the FBL
- ●The sender's email platform receives the report
- ●The complaining address is automatically added to the suppression list
- ●Future emails to that address are blocked
Most major mailbox providers support FBLs. Registering for FBLs is a standard deliverability best practice. Your email provider typically handles FBL registration and processing automatically.
Related Terms
Complaint Rate
The percentage of recipients who mark your email as spam, a critical reputation metric.
Suppression List
A list of email addresses that should never receive emails, including unsubscribes, bounces, and complaints.
Sender Reputation
A score ISPs assign to your sending IP and domain based on email behavior.
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Transmit handles authentication, warmup, and reputation isolation automatically.