Feedbackloop

Complaint Feedback Loops are feedback in form of ARF reports, usually sent by E-Mail to a previously registered address. Feedbackloops are sent by ISP's to senders when mail from the sender in question has been marked as SPAM. Some feedbackloops are registered by IP, meaning a complaint report is sent when a mail from a certain IP is marked SPAM, and others by domain, meaning a complaint report is sent when a mail from a certain domain is marked SPAM.

Complaint Feedback Loops have two functionalities:

• To detect IPs, domains and brands that are sending unwanted E-Mail.
• To unsubscribe recipients that have marked message(s) as SPAM.

List of free and independent feedbackloops

Directly from the ISP

The following list of Feedbackloops is facilitated directly by the ISP receiving the SPAM complaint. If, for example, the earthlink FBL is registered, only Earthlink ARF Reports will be received.

ISP Complaint Feedback Loops

Name	Registration Link	IP/Domain based	Note
1&1	Register via the Postmaster page.	IP	Only for mail.com, web.de and various gmx domains.
Earthlink	fblrequest@abuse.earthlink.net	IP	E-Mail registration. Send it from the address that's to be registered and don't forget to mention your IPs!
Google Postmaster	https://gmail.com/postmaster/	IP/Domain	No E-Mail reports.
mail.ru	https://postmaster.mail.ru/	Domain	Read https://help.mail.ru/enpostmaster/technical-settings/fbl.
Microsoft	https://postmaster.live.com/snds/JMRP.aspx	IP	E-Mail reports are not in ARF.
Yahoo	https://senders.yahooinc.com/contact	Domain

Provider independent

Provider independent FBLs are facilitated by independent third parties.

PI Complaint Feedback Loops

Name	Registration Link	IP/Domain based	Note
Abusix	Add a CFBL header to outgoing E-Mail	IP	https://abusix.com/feedback-loops/ - XARF reports. Will be available soon.
SpamCop	https://www.spamcop.net/anonsignup.shtml	IP	IPs from Mail reported to SpamCop are added to the SpamCop blacklist

Paid Feedbackloop subscriptions

In addition to the above list, it's possible to register for a list of collective Feedbackloops from various small ISPs via Validity's Feedbackloop Service (fbl.validity.com). It used to be a free service, but since September 2023, receiving ARF reports via E-mail via this service costs $1.500 per year. The service covers the following ISPs:

• Bluetie
• Comcast
• Fastmail
• gandi.net
• LaPoste.net
• Libero (Italiaonline)
• Liberty Global (Chello, UPC, and UnityMedia)
• Locaweb
• OpenSRS/Hostedmail (Tucows)
• Rackspace
• Seznam
• SFR
• SilverSky
• Swisscom
• Synacor
• Telecom Italia
• Telenet
• Telenor
• Telstra
• Terra
• UOL
• Virgilio
• Virgin Media
• Yandex
• Ziggo

Standardisation

In May 2023, work on standardisation of registration to Complaint Feedback Loops via Complaint Feedback Loop Address Headers was started. Acceptance of this proposed standard would obsolete all paid or otherwise complicated feedbackloops, providing a standardised, open and free subscription mechanism.

Useful links

• wikipedia:Feedback_loop_(email)
• https://datatracker.ietf.org/doc/html/draft-benecke-cfbl-address-header
• https://abusix.com/feedback-loops/