feedback loopsRecently, we’ve gone back to the basics to shed some light on email terms and frameworks, like SPF and DKIM, that are essential to email delivery. Today, we’d like to highlight one of the most important tools you have in your email delivery toolkit: feedback loops. We’ll give a brief overview of what email feedback loops are, how you should implement them, and which ISPs provide them.

Feedback loops defined:

A feedback loop (FBL) is a service offered by some ISPs that report back complaints (when a subscriber hits the spam or junk button in their inbox) to senders. It’s provided to aid senders in keeping a clean list. Senders should use feedback loops to listen to their subscribers and to take action (removing subscribers) if there are complaints. It’s important to learn from the complaints you receive because they can help you evaluate (and rectify!) underlying issues with your sending frequency and content.

Feedback loop requirements:

What’s needed for a feedback loop varies based on the ISP. These are general guidelines that will make sure you’re set up for success when applying for a FBL:

  • You must own the IP/domain, or have admin rights, in order to register for a FBL
  • There must be a working abuse@ or postmaster@ email address for the domain
  • The rDNS of an IP being entered needs to match the domain being used
  • Most ISPs specify that a good reputation is needed to be accepted on their FBL (Do you have the best reputation possible?)

Available ISP feedback loops:

Not all ISPs provide a feedback loop, and it’s important to note that they are resource intensive. Most ISPs that have FBLs let Return Path manage it for them, as you’ll see in the list below. Laura Atkins from Word To The Wise has good feedback loop information on her ISP Information page if you’d like more details.

Additional Information

  • Note: SendGrid automatically registers its customers for all ISPs that offer feedback loops.
  • *Gmail has a feedback loop that is only available for ESPs who are MAAWG members and are approved by Google as good senders. For more information on SendGrid’s first-hand experience with Gmail’s feedback loop, read this blog post from our VP of Delivery, Paul Kincaid-Smith.

For more information on feedback loops and ISP compliance, read our guide, The ABCs of ISPs.



Tanya is SendGrid's Email Deliverability Consultant.