Email marketers strive to stay ahead of the curve when it comes to their spam rates, sender score, and email deliverability. One useful tool is using data from an ISP’s email feedback loop.

The following information looks into the FBL meaning and discusses why you should engage with feedback loops as a best practice.

What is an email feedback loop?

An email feedback loop (FBL) is a service provided by a selection of ISPs. The FBL sends reports to email mailbox providers or email marketers about complaints made by their email recipients.

Okay—the term ‘complaints’ sounds a bit harsh. Nobody physically complains or drafts out a harshly worded message; they merely hit the button that sends your emails to their spam or junk folder.

However, not all ISPs deliver the same information or in the same manner. Some will provide the recipient email address and message in question; others won’t. We’ll tell you all about that a little later on.

How does an email feedback loop work?

  1. You send an email campaign out to all the addresses on your list.
  2. Some of the recipients decide your message is spam or junk and hit the button that sends it to the spam/junk folder.
  3. The internet service provider (ISP) sends this information to the sender, as long as they’ve signed up to their FBL system.
  4. With this new information, the email service provider or marketer can manually remove the complainant’s address from the list, or automate a system to manage it for them.

All that glitters isn’t always gold

It all sounds brilliant so far, right? What an excellent tool for email marketers out there.

Here’s the not so good news.
Not all ISPs provide FBLs, and they don’t all send their data in the same way. Also, tracking each of them down and signing up for them isn’t anywhere near as simple as you’d think it should be.

Hitting the spam button vs following the unsubscribe link

Sadly, far too many people use the spam button for the wrong reason. When we get a whole bunch of emails that we’re not interested in, it’s often far simpler to dump them all in our junk folder than unsubscribe from them, one at a time.

It’s another strong reason for monitoring your email campaign statistics and following all list hygiene best practices—making sure you’re only marketing to those who are engaged and interested in what you have to say.

FBLs don’t always deliver the information you’d like

There are 3 main email feedback loop formats:

  • Traditional IP-based
  • Domain-based
  • Aggregated

The first two send reports in the industry-standard Abuse Reporting Format (ARF). This provides the sender with the full message and the identification of the complaining user.

However, aggregated reports are more sensitive to sharing personally identifiable information (PII) of their users, so send batches of complaints relating to IP, domain or another identifier provided by the sender. In these cases, the specific data a marketer needs isn’t included, just an aggregate of the various statistics.

Microsoft uses its own format, Junk Mail Reporting (JMR), and Gmail operates quite differently to other providers, offering little specific data and mainly only to ESPs approved by Google as good senders.

What are the requirements to receive an ISP feedback loop email?

Each ISP has its particular way of processing their FBL process. The standard points you need to organize before applying for any of them are typically:

  • You must be the owner of the IP address, and the domain; or have administrative rights for each.
  • The rDNS of the IP must match the domain.
  • Some FBLs require a list of DKIM keys (Domain Keys Identified Mail) used to sign emails. DKIM is an email authentication method that adds security to your emails using a digital signature.
  • You must use an active feedback loop email address, for example, [email protected] or [email protected] that has the providers’ FBL email addresses whitelisted or have no spam filtering. This ensures the receipt of your FBL emails.
  • A good email reputation score is also required for most providers.

What are the benefits of having feedback loop email?

Removing the complaining email addresses

The biggest plus is removing all the complaining recipients from your lists. This prevents further complaints from them, lowering your spam rate, and improving sender score and deliverability.

Identifying your weakest or campaigns and problem lists

An FBL can draw attention to the campaigns that your recipients aren’t interested in. It could be something as simple as a weak email subject that encourages those list members to hit the spam button.

It’s another indicator that you should be A/B testing emails to ensure you’re sending with your best foot forward at all times.

If you build your lists from different sources, an FBL could help point out which ones are reacting poorly to which messages. You may be sending the wrong information to the wrong demographic. It’s a worthy addition to your testing tools.

Identifying compromised addresses

Where illegal spammers have compromised your IP addresses, an FBL email will draw attention to complaints of emails you didn’t even send.

How do I sign up for email feedback loop reports?

The email marketer or sender has to apply for each mailbox provider’s FBL. You’ll be expected to provide some necessary contact information as well as some of the technical requirements we discussed earlier.

When you’ve got all of that sorted, and for all of the services which provide FBLs, then you’ll need to decide how you’re going to manage your new data. Whichever you choose—manually monitoring or parsing messages to automate the deletion of unrequired addresses—they all need removing.

It’s difficult to track down a definitive list of FBL providers and how each operates.

However, has a list of ISP sender support information and is as good a place to start as any. It includes quite a few handy links, including those to each’s FBL signup, where available.

Summing up

We believe any system or step an email marketer can take to protect their domain reputation, sender score, and email deliverability is one in the right direction.

Each system or step you add to your best practices could be the difference between landing in an inbox or someone’s junk—creating a lead or making a sale.

Engaging with relevant FBLs is a valuable exercise and a tool we should all be utilizing. We all want the cleanest and most hygienic lists possible, so the email feedback loops should be another valuable weapon in your email marketing arsenal.

Email Checker vs DIY List Cleaning