The sub-folders aren't visible but when I created a second sub-folder with the same name, a box appeared advising me that a sub-folder of the same name had been created so could not be called that. Please let me know where I can find it.
MacBook Air, just bought the mac book air
Are you describing "mailboxes" in Apple's Mail app? That's odd, since this is the forum category for iPods.
The location of a new mailbox is determined by your Location selection when you created the new mailbox. In the panel that appears when you give command to create a new mailbox, there is a drop-down selection field for Location. Click that field. That is probably where you put your previous mailbox, so if the new one with the same name is duplicated at that location, that's the location you need to look.
If this question is about iPod (or iTunes), please post back with more details.
I have created sub-folders under one email address but can't find the sub-folders. Can you tell me where they are please.
