The Comcast Feedback Loop is Available Exclusively from Return Path

We are very pleased to announce that Comcast now offers a complaint feedback loop, powered by Return Path. (For you deliverability nerds, you might note that we got beaten on this announcement by our friends at We appreciate the plug!)

Those of us who work in the industry feel like everyone should, by now, grok what a feedback loop is and why it’s so useful for both senders and end recipients of email. But we know that’s not completely true yet, so this seems like a good time to review the history and initial purpose of feedback loops.

When a user clicks the “report spam” button (or equivalent) in their mail client, a copy of that message (a spam “complaint”) is transmitted to their ISP. This type of system is generally only used by web-based mail clients such as Yahoo! Mail or Hotmail, or in custom desktop interfaces such as AOL’s, though some anti-spam vendors offer plug-ins for Outlook or Thunderbird. The ISP can use these reports, in aggregate, to update and improve their spam filters.

However, as we’ve known for years, it’s much better for receivers if they can stop the spam from being sent at all rather than only filter it after they’ve incurred the costs of receiving it. To achieve this, ISPs will regularly report problems to each other – an administrator at one ISP might contact a colleague at another ISP to say “Hey, somebody on your network is spamming my users, where should I send the evidence?” AOL was among the first to automate this process, offering real-time feeds of complaints to the ISP, web host, or (eventually) ESP or marketer from whose network the offending messages originated. Several more ISPs followed AOL’s lead, and offered their own automated complaint feedback loops.

These complaint feedback loops allow administrators to sign-up to receive copies of all complaints originating from their network. The intention is that the administrator will prevent the sending of similar offending messages – the ISP doesn’t care how, as long as the problem stops and their customers stop complaining. For many senders, this means removing the complainer from their mailing lists – but this data can also be extremely useful for improving their mailing and address acquisition practices, in order to avoid receiving similar complaints from other recipients in the future. For an ISP or ESP, it means locking down any offensive customer who has been sending objectionable email from their network.

Over time, ESPs and other legitimate bulk senders have come to rely heavily on this data, because they know that complaints from recipients have a direct and immediate effect on whether they are able to send mail to all of the subscribers on their list. If a sender receives too many complaints, all their future mail could be rejected. A rise in complaints has an immediate negative impact on a sender’s reputation. However, the common myth that just one single complaint can doom your mail forever is demonstrably untrue – ISPs know that sometimes their users make mistakes, so their systems are designed to take other factors into account.

As the audience for complaint feedback loops changed from a few dozen ISPs to a few thousand bulk senders, the technical burden and customer service load required to operate a feedback loop has increased dramatically – and as such, there is now a significant financial hurdle for ISPs to offer these programs, or any other sender support services. At the same time, ISPs see complaint reductions on the order of 30% to 40% when they do offer a feedback loop program. Spam prevention is always a cost center, so it can be difficult for them to decide whether to invest in a feedback loop and customer service staff, or invest in alternate new technologies.

That’s where Return Path comes in. We now host feedback loops for Comcast,, and Mailtrust and we are in the process of setting up half a dozen more over the next few months. A large portion of our business has always been to help senders understand how to handle the feedback they’re receiving, so this is a customer support task that we are uniquely capable of handling – and our ISP partners appreciate it.

We see feedback loops as a huge win for both senders and receivers and email users. Receivers lower their costs by stopping more unwanted mail from even being sent, reduce inbound inquiries from marketers who are blocked, and provide a better experience for their customers who want a reduction in spam without missing out on email they actually want to receive. Senders get data that helps them lower their complaint rates, improve their deliverability, audit their practices, and, most importantly, create a better experience for their email subscribers. Email users win by eventually getting less spam.

If you are a sender or network operator you should sign up for this feedback loop right now. It’s a simple process … just go fill out this form.

If you are a receiver and you want to implement a feedback loop, contact us for more information.

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