Reorder mailboxes, filter by favorites
Another fix to iOS's email is the new ability to reorder mailboxes in your list of accounts, so they appear in your preferred order rather than the seemingly random order of previous versions.
iOS 6 also uses the VIP virtual mailbox that debuted in OS X Mountain Lion: Mail from anyone you specify as a VIP appears in the virtual VIP mailbox for quick access. (These are aliases, so the actual message remains in the original mailboxes and folders.) Tap a name in a mesage and choose Add to VIP in the popover that appears; VIPs in OS X's Mail also sync with iOS.
Another minor change: The flagging feature now gets its own button at the top of the message pane.