This article will show you how to find the number of items located In a specific folder on Exchange Server 2010, 2013, 2016 mailbox.
Open EMS and type the cmdlet below (replace the USER and Folder name)
Get-MailboxFolderStatistics USER | select name , itemsinfolder* | where{$_.name -like "deleted*"}
As you can see there are 117 Items In the Deleted Items folder.