A feedback loop is a data feed set up by Internet service providers (ISP) which forwards complaints originating from their users back to the sender of the original message. This complaint data is then processed by the sender so they can remove and/or permanently unsubscribe the user from the list (or lists) in question. This helps to avoid future complaints, which can seriously affect delivery.
It also gives ESPs (Email Service Providers) the ability to keep track of how many complaints are received for a given client (or campaign) so they can take the appropriate action.
People who generate a lot of complaints can cause many problems with delivery, especially if they are part of a shared IP pool used by multiple customers.
On average, a complaint rate over 0.25% (1 in 400) at any given ISP for a given mailing, is considered a problem.
Under your contact activities in your delivered campaign, you will be able to filter FBL’s by providers. These include:
IBM SmartCloud Notes
How we calculate the complaint rate:
total number of complaints / total number of email sent to the FBL domains
It is not divided by the total number of emails sent as this would not give the most accurate representation of your true complaint rate at each ISP.