UW IMAP Concepts
Black Box and Clearbox Models
We mention black box and clearbox modes only because, once you unpack the UW IMAP development environment, youâre likely to run across several references to a black box mode in the accompanying documentation. You may also see mention of it in discussion lists and, if youâre so inclined, in the server source code itself. Clearbox mode, the default, is the mode in which we strongly urge you run UW IMAP. Black box mode has to be explicitly enabled.
References to black box IMAP servers usually occur in two contexts. One context refers to a machine whose mission is solely that of an IMAP serverâit does not provide shell, Web, or other Internet services. In the other context, black box refers to a configuration mode and namespace intended solely for internal use at the University of Washington. Itâs easy to get the impression from the UW documentation that black box is a valid configuration choice for users outside the University of Washington. Itâs not. UW black box mode was designed for a single server at UW. It is not a general mechanism, nor is it intended as such. UWâs public servers donât even use black box mode, even though they are black boxes. Later, weâll give you chapter and verse of the warning from Mark Crispin himself.
In the general context of Internet messaging, though, the black box distinction is usually loose enough to include any server that:
Has no interactive logins (with the exception of the administratorsâ ...