In any proceedings for defamation against any person who has published the matter that is the subject of the proceedings solely in the capacity of, or as the employee or agent of, a processor or a distributor, it is a defence if that person alleges and proves—
(a) that that person did not know that the matter contained the material that is alleged to be defamatory; and
(b) that that person did not know that the matter was of a character likely to contain material of a defamatory nature; and
(c) that that person's lack of knowledge was not due to any negligence on that person's part.