The system must disable Account Modification. Account Modification includes adding or modifying internet accounts in Apple Mail, Calendar, or Contacts in the Internet Account System Setting Pane or the AppleID System Setting Pane.This prevents the addition of unauthorized accounts.[IMPORTANT]====Some organizations may allow the use and configuration of the built-in Mail.app, Calendar.app, and Contacts.app for organizational communication. Information system security officers (ISSOs) may make the risk-based decision not to disable the Internet Accounts System Preference pane to avoid losing this functionality, but they are advised to first fully weigh the potential risks posed to their organization.====