Within Exchange (on-premise or Online) it’s sometimes helpful to export the delegate permissions that a user can set within their mailbox. Get-MailboxFolderPermission is the cmdlet which will export that information for a particular folder. The identifier needs to be in the format “email@example.com:\Marketing\Reports”.
That said there’s not an easy way to export the permissions on ALL folders within a mailbox and the output for that command isn’t very helpful for further processing.
So; script. It’ll take a mailbox as a parameter and output the permissions on all the mailbox folders (and subfolders) as objects.
This is the explanation about the initial version of the script, here.