Ah, they won't be sending you unsolicited porno tapes. And if they wanted to send you junk mail promoting their services, as long as the mail didn't contain the offending images they could do so. Since they are not, it is clear that doing so is not a beneficial marketing strategy and you have no need to worry about your mailbox being stuffed with said items.
What makes you think that? Unless the law is enforced, why wouldn't porno producers send out free samples on CD-ROMs or DVDs the way AOL sends out AOL 8.0 CDs?