Windows Icone Double Fleche

• Windows Icone Double Fleche En

I've got a user who is out of the office. To answer her emails, we've given another user rights to her boxes, and we've added that to the user's account under the 'Open these additional mailboxes' setting.In there, we've found all of the user's folders appear as folders with a double-ended, blue, arrow. I've attached a screenshot of the icon.What does this icon indicate, and how are these folders made?

Windows Icone Double Fleche En

Why can't we rename them? Outlook help, and even Google, have not been able to explain this.In active directory, the user has all permissions to the mailbox except the 'associated external account' permission.