As of 2016 these are the location of feedback loops that mail service owners can use to get alerts about abuse originating from their networks.
AOL - AOL Postmaster - Feedback Loop Request
Comcast - Comcast.net Feedback Loop - Feedback Loop Request Form
EarthLink - Collection of Best Practices for Email Senders on the EarthLink Network
FastMail - FastMail Feedback Loop Request Form
Gmail - Gmail Spam FBL Enrollment Form for ESPs
Hotmail / Outlook.com - Sign in to your Microsoft account
Synacor - Synacor - Feedback Loop Request Form
Time Warner - Time Warner Cable - Feedback Loop Request Form
Yahoo - Postmaster | SLN3438 - Complaint Feedback Loop program (Yahoo Complaint Feedback Loop (CFL))
Zoho - http://fbl.zoho.com/
AOL - AOL Postmaster - Feedback Loop Request
Comcast - Comcast.net Feedback Loop - Feedback Loop Request Form
EarthLink - Collection of Best Practices for Email Senders on the EarthLink Network
FastMail - FastMail Feedback Loop Request Form
Gmail - Gmail Spam FBL Enrollment Form for ESPs
Hotmail / Outlook.com - Sign in to your Microsoft account
Synacor - Synacor - Feedback Loop Request Form
Time Warner - Time Warner Cable - Feedback Loop Request Form
Yahoo - Postmaster | SLN3438 - Complaint Feedback Loop program (Yahoo Complaint Feedback Loop (CFL))
Zoho - http://fbl.zoho.com/