The CloudStack Quota plugin has an improper privilege management logic in version 4.20.0.0. Anyone with authenticated user-account access in CloudStack 4.20.0.0 environments, where this plugin is enabled and have access to specific APIs can enable or disable reception of quota-related emails for any account in the environment and list their configurations.
Quota plugin users using CloudStack 4.20.0.0 are recommended to upgrade to CloudStack version 4.20.1.0, which fixes this issue.