In the package header, look for Read Status. This is a quick indicator of how many of the package recipients have viewed the package. The possible status indicators are All, Some, or None.
Click More to view all recipients of the package, including members of groups marked as "Expansion Allowed" in the sender's address book, along with whether or not they have viewed the package.
All recipients of the package have viewed the package.
Some but not all of the recipients of the package have viewed the package.
None of the recipients of the package have viewed the package.