When a user logs on to a Microsoft Exchange 2010 mailbox by using a POP3 or IMAP4 client, the LastLogonTime, LastLogoffTime, and LastLoggedOnUserAccount property of the mailbox are not updated. Therefore, the Get-MailboxStatistics command returns an incorrect value when you run the command to query these properties.
This issue occurs because the Exchange store cannot recognize client strings from POP3 and IMAP4 clients.
To resolve this issue, install the following cumulative update:
2661854 Description of Update Rollup 2 for Exchange Server 2010 Service Pack 2
For more information about MailboxStatistics properties, visit the following Microsoft website: