Get-MailboxFolderStatistics rdanie21 -IncludeOldestAndNewestItems | Sort name | Select Name, Folderpath, ItemsInFolder, FolderSize, OldestItemReceivedDate You want to list the mailbox folders for a mailbox and include the date of the oldest item within that folder.
Run the following:
Get-MailboxFolderStatistics mailbox -IncludeOldestAndNewestItems | Sort name | Select Name, Folderpath, ItemsInFolder, FolderSize, OldestItemReceivedDate
Ex-Shell 