'''If you are using 'View > Folders > Unified''' Then you cannot add a folder as a subfolder to a virtual unified 'Inbox' You need to click on the chevron '''>''' located to the left of the Unified 'Inbox' to expand and see the individual Inbox folders. Those individual account Inbox folders will have the account name not the name Inbox. Right click on the account name and select 'New Folder' That should allow you to add a new subfolder to that individual account Inbox. '''IF you are using 'View' > 'Folders' > 'All'''' The mail accounts should be listed with their own set of folders. Right click on the 'Inbox' and select 'New Folder' It would be useful to know what happens when you right click on Inbox. Is the 'New folder' option greyed out ? Or is the option available and you enter details, but 'Create folder' is not creating folder ? Are you talking about an Imap mail account ? right click on imap mail account name folder and select 'Subscribe' click on 'Refresh' Do you see the new folder in the list ? If yes, select it and clickon 'Subscribe' clickon 'OK'