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What is Feedback Loop and why should it be implemented?
What is Feedback Loop and why should it be implemented?

Tool that helps monitor and improve the quality of mailing campaigns and increase the effectiveness of message delivery.

Weronika Kapias avatar
Written by Weronika Kapias
Updated over a week ago

Feedback Loop (FBL)

Mechanism used by email service providers such as Gmail, Yahoo and Outlook to provide feedback to senders on their sent emails.

In practice, if a recipient marks an email as spam, the email provider informs the sender of this notification via Feedback Loop. This allows the sender to identify which specific email has been marked as spam and to take appropriate action, such as removal from the mailing list.

In the context of Google, Feedback Loop enables businesses to track feedback from Gmail users on their emails, helping to keep mailing campaigns clean and effective and minimising the risk of their messages being treated as spam. This process involves a situation where exceeding a certain FBL threshold within your campaigns results in your emails being moved to the spam folder. The higher the number of words of a potentially spammy nature, sending too many in a short period of time or creating only graphic email content, the higher the score. Introducing and using Feedback Loop is a standard way of maintaining a sender's good reputation for email delivery.

Gmail does not send notifications about the email contact through which your email was marked as spam, but you will receive a general notification about a specific campaign, product or region.

How does it work?

User submissions:

If the recipient marks an email as spam or marks it as unwanted.


An email provider, such as Gmail, collects these notifications from users.

It then informs the sender that one of its users has marked their email as spam.

Sender response:

With the information received, the sender can identify the specific message that has been marked as spam.

Sender's action:

The sender can take various steps in response to the feedback, such as removing the subscriber from the mailing list, adjusting the content of the email or improving sending practices.

Preventing future problems:

The sender can also use the information from the Feedback Loop to improve their email sending practices, avoiding problems related to being flagged as spam.

Configuration requirements for Gmail

Before you start implementing Feedback Loop, make sure you have correctly configured and verified SPF, DKIM and ReverseDNS settings. ReverseDNS is a process that enables server recognition by assigning IP addresses to domain names. If these authentication entries are not correct, it will be impossible to complete the Feedback Loop configuration process.

Start your setup by registering for Postmaster Gmail. Use the available help from Google, available here, to create a Postmaster account. During the process you will be required to confirm domain ownership, so make sure you have the ability to add a TXT record to your DNS settings.

Also check out the list of best practices in Gmail's bulk sender guidelines, which are listed here.

It will be required to embed a new type of header, the so-called Feedback-ID, which contains parameters, the so-called Identifiers, which allow individual campaigns to be identified. IDs that contain a deviated spam parameter, causing a problematic delivery incident, will be reported in the FBL Postmaster Tools control panel. Full instructions for implementing FBL for Gmail from Google, can be found here.

Configuration requirements for Yahoo

A full description of DKIM and how it relates to Feedback Loop Yahoo can be found here. In order to receive Feedback Yahoo information, you will need to submit a request that will allow you to receive such data. Steps to apply:

  1. If you don't already have an account, register on Yahoo.

  2. Fill in your details on the form, such as your company name, contact name, phone number and contact address.

  3. Enter the email address where you would like to receive complaint notifications from Yahoo.

  4. Determine the selector and domain of the DKIM key, while confirming that this request is new. If you plan to register all DKIM selectors for a particular domain, use the '*' symbol as the selector name.

  5. Click the button to download the verification code. This step will enable Yahoo to send an email with the verification code to the address where the DKIM is registered.

  6. Enter the verification code you received from Yahoo in place of the verification code and then click the 'Create Request' button.

  7. If all items entered were correct, you will receive a message that Yahoo has received your request to use the Yahoo Feedback Loop, otherwise known as the Complaint Feedback Loop (CFL). You will receive another email within 48h confirming your request. More information can be found here.

Configuration requirements for Hotmail

This free service for delivering spam reports reported by users of,, and just like Yahoo is based on making the appropriate request. You can also use the automated complaint handling, for more information see here.

Once the IP addresses of an email server have been registered with the Hotmail feedback system, Microsoft will take two actions:

  • Sending spam complaints to the address provided. These complaints may contain some information, such as the recipient's changed email address, but other than that the original content of the email will remain mostly intact. Whenever a user reports a message from your server's IP address as spam, a spam complaint notification will be sent.

  • Provision of aggregated data through Smart Network Data Services (SNDS). This department allows you to check the reputation information of each IP address as assessed by Microsoft.

Steps to apply:

  1. If you do not have one, create a Microsoft account here.

  2. Visit the Feedback Loop Hotmail page, here.

  3. Complete the application with the following details: company name, contact email and FBL feedback email.

  4. In the "Complaints format" section, select the format in which you would like the complaints to be sent to you:

  • ARF -> default setting

  • Attachment

  • Original message

5. Optionally, if you wish to reduce the number of complaints sent per day from one IP
address or between all IP addresses, adjust the relevant fields. In most situations,
these fields are set to default values that do not actually have limits.

6. Before clicking the 'Add new network' button, enter each IP address or range of IP
addresses you wish to register individually.

7. Select an authorisation address for each registered IP address or range from which
you intend to receive emails. To complete the feedback registration process, you will
need to click on the confirmation link sent by Microsoft to this address

8. Press the "Start Setup" button to submit the form. Once the form has been
submitted, three events will occur:

  • You will automatically be logged into your newly created SNDS (Smart Network Data Service) account.

  • Microsoft will send a digital agreement to the specified contact email address.

  • Microsoft will deliver verification emails to the specified authorisation addresses.

9. Add information regarding the digital contact that will be sent by Microsoft to your
previously provided emails. If you have not received such messages, send a resend
request by clicking 'View IP status' in SNDS and then selecting 'Send resend request'.

That's it, you have successfully registered for the JMRP service, also known as the Hotmail feedback loop, as well as the JRMP service.

Need more help?

If you have any further questions about the deliverability, please do not hesitate to contact us at

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