I've just been searching through the sourcecode trying to find any evidence that MAILBOX_FORMAT_NETNEWS actually changes how anything works.
It looks like it's used in charset_searchfile and charset_extractfile and asserted in a couple of places that don't seem to make heaps of sense to me - things like being unable to find the filename for the file, and not copying the cache record when copying messages between mailboxes. Does anyone remember why it's done this way, and if it's still needed? It would be nice to be able to simplify... Thanks, Bron.