I have two accounts (of the same domain) in my Mail app (IMAP). One of them was greyed out and inaccessible but I could still get the messages from the combined Inbox. So, I deleted that account and set it up again - now, it's not greyed out but I still am not allowed to access it - and I can get the messages from the combined Inbox. Sometimes, it won't receive messages - there was a two hour period where it just wouldn't work (email on my laptop was just fine so it's not the server). Mail seems very buggy...anybody else have issues like mine?