Summary information about users is displayed in an address book and in the Address Selector when you position your mouse pointer over that name. The same information will display in the To, CC, BC, or From boxes of a message if you first click on the name. This display is called Quick Info.
This shows Quick Info in a mail message:
This shows Quick Info in the Address Book:
This shows Quick Info in the Address Selector:
If multiple users are listed in the To, CC, BC, or From boxes of a message, click the box to open the list of users, select one of them, then position the mouse pointer over the selected user.
Quick Info is enabled by default. To disable Quick Info,