+
+ # Move the Dovecot user *src* to *dst*. This relocates the user's
+ # directory within the Dovecot mailstore (on the filesystem).
+ #
+ # This fails if the source user does not exist, or if the
+ # destination user already exists before the move.
+ #
+ # But is it an error if the target domain does not exist? That's a
+ # bit subtle... The domain may exist in the database, but if it
+ # has not received any mail yet, then its directory won't exist
+ # on-disk.
+ #
+ # There are two possible "oops" scenarios resulting from the fact
+ # that we may run either the Postfixadmin move first or the
+ # Dovecot move first. If we move the user in the database, we
+ # definitely want to move him on disk (that is, we should create
+ # the directory here). But if we move him on disk first, then we
+ # don't know if the database move will fail! We don't want to move
+ # his mail files if he won't get moved in the database.
+ #
+ # Faced with two equally-bad (but easy-to-fix) options, we do the
+ # simplest thing and fail if the destination domain directory
+ # doesn't exist. If nothing else, this is at least consistent.
+ #
+ # @param src [User] the source user to be moved.
+ #
+ # @param dst [User] the destination user being moved to.
+ #