Create a import job @ https://protection.office.com/import
Install AzCopy: https://aka.ms/downloadazcopy
Make a command looking like this:
AzCopy.exe /Source:”K:\Support\PSTFOLDER” /Dest:”https://LONG-MS-URL” /V:C:\ /Y
And upload! After uploading continu from https://protection.office.com/import
