Most of the major ISPs have some sort of feedback loop (FBL) in place, where their users can report spam (learn more about feedback loops, and how they can affect your deliverability). Email marketing services like MailChimp have to sign up for all those ISPs’ feedback loops, so we can properly clean our users’ lists of complainers.

Just recently, MailChimp has experienced some amazing growth, and so we’ve had to add more IP addresses to our delivery queue. That means we’ve had to re-submit all our IPs to all the ISP FBLs again.

Normally, each ISP has its own FBL, with its own set of requirements, application process, review process, and reporting format.

This time around, we’re noticing that nearly all the FBL application emails we’re getting back from these ISPs look exactly the same. Then we figured out why: they’ve switched to ReturnPath’s FBL service. This is nice, because: 1) we’ve been ReturnPath partners for a long time, and 2) hopefully, we’ll all have a centralized FBL system to work with (and submit IPs to), instead of managing so many different accounts with so many different ISPs.