If memory serves, this happens because when the Spam controls were put in place (only registered subscribers can post), then Netapp employees were no longer able to post because they receive the list through an internal remailer/exploder. It was decided at the time that having Netapp able to post was more important than preventing the occasional Spam.

What I find really interesting is that the only Spam we ever seem to get is variations on the Nigerian thing. I guess nobody thinks Network Appliance administrators need to make money fast, or make certain things bigger.