When you accept to share a Grantor's mail folder, the mail folder is displayed in your Overview pane. When you open the folder,you see the content of the folder. This information is not actually saved in your mailbox.
You can open the email and if you were granted permissions of Manager or Admin, you can reply to, forward, or delete the message. Copies of the messages you send are saved in the Grantor's mailbox and if you delete something from the Grantor's mailbox or mark it as spam, it is moved to the Grantor's Trash folder or Junk folder.
If you have access to more than one of the Grantor's folders, you can move the contents from one folder to another folder in the Grantor's mailbox. You can copy an email message from the Grantor's folders to your mail folders, and the Grantor's mail folder also retains a copy.
You can create folders within the shared mail folder and the new folder you created appears in the Grantor's mailbox.