Question:
I would like to know what report showing unopened ('unread') messages in users' mailboxes.

Answer:
The report template you are looking for is called General Mailbox Content and you will find it on the Templates > Mailbox Content  menu. Information is dynamically collected through an EWS connection to the Exchange server.

You will apply the following settings:

• Selection tab: Select the mailboxes to be scanned.
• Folders tab: Select the folder or the set of folders to be scanned - for example, the Inbox. Select the Sub-folders check box to get the entire folder hierarchy under the Inbox.
• Filter tab: Set the following filter: [Read] Equals False.
• Options tab: Sort mailboxes by name, item count, item size or folder count.
• Content tab: Check Mailbox to obtain a mere total per mailbox, Folder to obtain a total per folder or Item to list each unopened Outlook item.
• Presentation tab: Your own choice.
• Output tab: Your own choice (Screen, Exploring form, Printer, Disk file, Email recipient, Exchange folder, Sharepoint, Database table).