Comment 53 for bug 13983

Boleslaw, you misunderstand. A protocol has nothing to do with a user interface. These are two distinct things.
Look at the POP-protocol: it has no folders, it has no trash and it is not designed to leave mail on the server. But many mail clients have local folders, local trash, and leave mail on the server. The protocol is only the transport mechanism for mail, it has nothing to do with the way a mail client offers mail to the user.

Now look at IMAP. Many old clients used it similar as POP, they fetched mail from the server as they did with POP. Folders were only local in these old clients. Modern clients work different, they leave mail on the server, they use folders on the server, and since trash is only a normal folder, they can move deleted mails to the trash folder on the server. Why should they restrict the user interface to the technical limits of the underlying protocol? There is no reason to do that.