It was observed that sometime mistake happened by users where the requirement was for sharing calendar but owner of mail file selected setting
"Mail, Calendar, To Do and Contacts" in "Components" section on "Access & Delegation->Access to your mail & calendar->Change Access" tab while
delegating the access.
In this case other users can read the mails which is a risk due the mistake happened.
To avoid such mistake we can segregate the components access individually like "Mail", "Calendar", "To Do" and "Contacts" and check box options can be provided so that user can delegate access to whatever components required. Please consider if feasible.