Why do I have a local folder, a global folder and a proprietary folder?
Local folder exist in any e-mail program, essentially it for POP3 account that stores the e-mail locally on the PC. Global folder is a feature of eM Client, if you have multiple e-mail account, it allows you to see all of your e-mails in different inbox in one location. You can disabled Global folder by the menu: Tools -> Settings -> General -> Show Global folder. You may also disabled the local folder at the same page, but you’ll also disabled all of the local folder, including Calendar, Contact, etc.
I’m not sure where you getting a proprietary folder from. Does that falls under an IMAP e-mail account folder?