In the Email Experience Manager (EXM), if the same contact is present in multiple lists, unsubscribing from an email campaign might not remove the contact from all the lists at once. As a result, email messages might continue to be sent to the recipient.
To resolve the issue, consider one of the following options:
Be aware that the hotfix was built for the specific Sitecore XP version and must not be installed on other Sitecore XP versions or in combination with other hotfixes. In case any other hotfixes have already been installed on a certain Sitecore XP instance, send a request for a compatibility check to Sitecore Support.
Note that the ZIP file contents must be extracted to locate installation instructions and related files inside. The hotfix must be installed on a CM instance and then synced with other instances using standard development practices.