--- title: ISP Feedback Loop description: Formed in November 2002, the ESPC's membership is comprised of many of the largest and most innovative technology providers in the email industry, including Email Service Providers (ESPs), Mail Transfer Agents, application and solution developers, and deliverability solutions providers. --- # ISP Feedback Loop #### Member Resources #### Regulatory Resources #### Industry Resources ISP Feedback Loops/Complaint Feedback Loops (FBL) is a process which allows mailbox providers a method to forward user generated complaints back to the sender or Email Service Provider.  In order to receive the FBLs, the senders or Email Service Providers must first subscribe/register with the organizations which offers it.  It is common best practice to treat/honor the FBLs as a user requested unsubscribe. Current list of ISPs and organizations offering Feedback Loops are listed- List URL and reference links to ISPs and Organizations supporting Feedback Loops [Comcast](http://feedback.comcast.net/) [Cox](https://www.emailfeedbackloops.com/how-to-apply-for-cox-feedback-loop.php) [Gmail ](https://support.google.com/a/answer/6254652?hl=en#)[FBL Article](https://support.google.com/a/answer/6254652?hl=en#) [Hotmail](https://answers.microsoft.com/en-us/outlook_com/forum/all/hotmail-feedback-loop/4317cb8b-ffbc-487b-be1f-7f1d2759f494) [Microsoft FBL Article](https://learn.microsoft.com/en-us/dynamics365/customer-insights/journeys/feedback-loop) [Validity Feedback Loop Service](https://fbl.validity.com/) [Yahoo!](https://senders.yahooinc.com/complaint-feedback-loop/)   ## Still, have questions? Can’t find the answer you’re looking for? [ Get in touch ](https://espcoalition.org/contact-us?hsLang=en)