We all remember how email marketing used to work: we’d gather email addresses wherever we could, and we’d send mail to them forever. Just like those multiple-choice standardized tests from grade school, there was no penalty for guessing wrong — if a subscriber didn’t want your email, so what? There was no downside.

Well, times have absolutely changed. We’re drowning in unwanted email; one estimate from 2018 claims that 45% of all email messages are spam… and because malicious spam can contain malware in the “unsubscribe” links, consumers have been trained to avoid the unsub link — even in messages from legitimate senders.

Gmail, Hotmail, Yahoo Mail – Whose Side Are You On?

The big mailbox providers aren’t helping matters. They encourage your subscribers to file spam complaints, by putting spam buttons prominently in the user interface. No thanks to Google, Verizon/Yahoo, and Microsoft, subscribers are more likely to click the spam reporting button than to unsubscribe.

What happens if one of your subscribers reports your message as spam? Several things, all of them bad:

  • The subscriber won’t see your emails any more; the subscriber’s MBP routes future messages from you to the spam folder automatically.
  • The mailbox provider will count the spam vote against you, which helps prevent other subscribers from seeing your email.
  • Because all subsequent deliveries to this subscriber will not be seen by the subscriber, your engagement rate will drop off, which further reduces your reputation in the eyes of the mailbox provider.

How To Beat the Spam Button

What’s a legitimate email sender to do? Well, there is a way to fight back. Most mailbox providers, although notably not Google, are willing to share copies of subscriber complaints. This is called a “feedback loop.” Feedback loops report complainers to senders, so that senders can unsubscribe the complainers. Even though your (former) subscriber didn’t have the courtesy to take himself off your list, his mailbox provider might be willing to share the complaint with you, which enables you to treat the complaint as just another unsubscribe request.

This is a big win for email marketers. Subscribers who complain about your mail shouldn’t be on the list. Wish them well, and unsub them immediately, and then focus on engaging your higher-quality subscribers.

To begin, sign up for the FBLs below. If you have no developer resources available, you could direct the FBL messages to a mailbox that someone can process manually, but the far better solution is to hire someone to parse the incoming messages and automatically unsubscribe the addresses associated with the complaints.

List of Email Feedback Loop (FBL) Providers

ReturnPath hosts an ambitiously-named “universal” feedback loop, which includes reporting from Cox and Comcast plus numerous European and Russian mailbox providers. If your ESP has not done so already, or if you send mail from your own infrastructure, sign up here.

ReturnPath FBL

Yahoo/Verizon/AOL share a “CFL” (Complaint Feedback Loop) system; sign up here.

Yahoo/AOL Postmaster

United Online (Netzero/Juno) combines its feedback loop into an IP whitelist application; sign up here.


Earthlink’s FBL can be set up via email; see the instructions here.


Last but arguably most important, Microsoft provides FBL services for Outlook/Hotmail, via the “Junk Mail Reporting Program.” Sign up here.


What about Gmail? Alas, Google has never provided feedback to mail senders… which is why we often advocate watching engagement rates for Gmail subscribers very closely. But that’s a topic for another time.