- Click the File tab.
- Click Account Settings icon, and then click Account Settings from the drop-down menu that appears.
- On the E-mail tab, in the list, select your account and click Change from the toolbar.
- Click More Settings.
- Click the Advanced tab.
- Click Add.
- In the Add Mailbox box enter the name of the account that holds the folder(s) you want to see.
- Click OK.
- Click Next and then Finish.
- Click Close.
- The added account will now appear in the left navigation panel under your own mailbox.
- Click any white triangles (see screenshot below) to see folder(s) and click on folder(s) to open.
If you get an error message - '...Cannot expand folder...' or if you simply cannot see a sub-folder when permissions have been set to allow you to access it, then you will need to contact the owner of the account to review the permissions they have set and ensure the 'Folder visible' box is ticked for the folder and all its parent folders.
See sharing folders.