To mark an email as private so that only users with 'Admin' permissions or those listed on the email can view the email.
Email messages in the project's Emails tool can be set to Public or Private. In addition, if you are a user with 'Admin' level permission to the Emails tool, you also have the ability to define whether all emails are public or private by default. See Configure the Email Tool's Settings.
Choose from the following:
If a user with 'Admin' permission on the project's Emails tool has created a 'Default Distribution' list (see Configure Advanced Settings: Emails), members of the default distribution list will receive ALL emails that have either been created in or sent from the Emails tool. Members will also receive all messages sent to the Emails tool via the inbound email address. This includes emails that have been marked 'Private'.