A few weeks back I did something in mail.app that messed up how messages are displayed. I have IMAP set up (as well as a POP account). When I select the mailbox for the IMAP account, it no longer displays any messages. To see messages from the IMAP account, I have to select the top level "inbox" icon (which displays messages in both the POP account and IMAP mailboxes) Oddly, if I select any of the subfolders under my IMAP mailbox (these are folders I've set up to organize messages by subject), it displays the messages there just fine. Here's another potential hint: when I select the IMAP mailbox, it is defaulted to sort by "message status" (even though, as I say, no messages are displayed). However if I right click and choose from the resulting pop-up menu the "sort by" submenu, there is no checkmark by "messages status" or any other choice. If I choose a different sort (e.g. "from"), when I navigate away from the IMAP mail box and come back, it has defaulted back to the message status sort (whereas the default behavior in other mailboxes is to keep the sort order last selected). What have I done?