Reading the Graph API docs, this only appears to support well-known folder names like “Inbox” and “Sent Items” etc or the actual folder ID. All the examples provided only mention those top level folders e.g. move your mail from “Inbox” to “Deleted Items”.
In theory it should work if you provide the mailfolderId. I tried using Graph Explorer to query the mailfolders resource e.g. https://graph.microsoft.com/v1.0/me/mailFolders/Inbox/childFolders to get the folder Ids, e.g:
But pasting that ID into the MailFolder input still returns the same not found error. It does mention name and spelling so it’s likely not using the API in the expected way behind the scenes.
Invalid mail folder name. Please ensure that this folder exists and that its name is spelled correctly.