When I run this cmdlet, I get the following result:
[PS] C:\Windows\system32Get-MailboxFolderStatistics user | ft FolderPath, FolderSize -autosize
FolderPath                    FolderSize
----------                    ----------
/Top of Information Store     156 B (156 bytes)
/Calendar                     244.2 KB (250,025 bytes)
/Contacts                     1.223 MB (1,282,252 bytes)
/Contacts/SenderPhotoContacts 30.41 KB (31,139 bytes)
/Conversation Action Settings 0 B (0 bytes)
/Conversation History         206.2 KB (211,147 bytes)
/Deleted Items                1.449 MB (1,519,602 bytes)
/Drafts                       472 B (472 bytes)
/Inbox                        618 MB (648,025,798 bytes)
/Journal                      144 B (144 bytes)
/Junk E-Mail                  131.9 KB (135,089 bytes)
/News Feed                    0 B (0 bytes)
/Notes                        1.847 KB (1,891 bytes)
/Outbox                       0 B (0 bytes)
/Quick Step Settings          0 B (0 bytes)
/RSS Feeds                    0 B (0 bytes)
/Sent Items                   6.754 KB (6,916 bytes)
/Suggested Contacts           9.316 KB (9,540 bytes)
/Sync Issues                  0 B (0 bytes)
/Sync Issues/Conflicts        0 B (0 bytes)
/Sync Issues/Local Failures   0 B (0 bytes)
/Sync Issues/Server Failures  0 B (0 bytes)
/Tasks                        7.994 KB (8,186 bytes)
/Recoverable Items            12.16 MB (12,748,519 bytes)
/Deletions                    0 B (0 bytes)
/Purges                       0 B (0 bytes)
/Versions                     0 B (0 bytes)  
But when I open the mailbox using both Outlook and OWA, the deleted items folder is empty.
I'm guessing it's corrupted or something like that. Is it possible to recover it somehow?
Thanks.