I don't like spam either.
This comes up every so often, but the reason given that the list was open to non-subscribers is because if it didn't then netapp employees wouldn't be able to post, as they receive it through a local exploder.
It can't be that hard to configure the mailling list to accept mail only from list subscribers or from any @netapp.com address?
A decision way back at the time was made that the pain of getting spam was worth the value of having Netapp employee's contributions.
...way back before spam was a real issue?
Regards Kristian