How do feedback loops influence IP reputation?

Every time someone clicks 'Report Spam' on one of your emails, the mailbox provider logs that complaint against the sending IP. Enough complaints and you get filtered, throttled, or blocked. Feedback loops (FBLs) are what let you intercept those complaints before they stack up.

Here's how they work: you register with a mailbox provider's FBL program, and whenever one of their users marks your email as spam, they forward a notification to you. You suppress that address immediately so you never mail them again. Without FBLs, you'd keep sending to people who've already flagged you, adding complaint after complaint until the damage is serious.

The complaint thresholds that matter: 0.1% is where mailbox providers start paying attention. 0.3% is where things get dangerous. Gmail's threshold is even tighter. They've made clear they want to see rates well below 0.1% consistently.

How to register for the main FBL programs:

• Yahoo: standard FBL via email notification
• Microsoft: JMRP (Junk Mail Reporting Program), managed through SNDS
• Google Postmaster Tools: no traditional FBL, but your spam rate is visible in the dashboard if you're sending enough volume to Gmail

Set up automated processing so complaints get suppressed the moment they arrive, not manually reviewed in batches once a week. Most ESPs handle this for you on shared infrastructure, but if you're on a dedicated IP or custom SMTP setup, you need to wire this up yourself.

So if If your complaint rate is already elevated and you're not sure why, the SOS hotline is free.