The customer is receiving Microsoft Defender "quarantine" email reports on a daily basis in order to ensure that their system is protected from potential threats. These reports provide valuable information about any suspicious files or activities that have been detected and quarantined by Microsoft Defender. By sending these reports regularly, the customer can stay informed about the security status of their system and take necessary actions to further protect their data. It is recommended to review these reports promptly and follow any guidance provided to maintain a secure computing environment.