Clients must deal with their own bugs.
And the client authors will say "that's because you are using that broken Paul Jarc server. Use a working server, such as UW or Cyrus or Communigate Pro or Microsoft Exchange or..."
Sorry. In such battles, the clients always win.
Let's go up one level: the client sends LIST, and gets back a list of mailboxes. Then a mailbox is deleted. Then the client tries to SELECT that mailbox. The server doesn't have a chance to say specifically that the mailbox no longer exists. Is BYE preferable to NO here?
Wrong analogy. IMAP does not promise any sort of state in LIST. It does with SELECT.
That's the way IMAP was designed in 1985. It's 18 or so years too late to change it. You have to comply with IMAP's rules, not try to change them to accomodate your desires.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.