It's not that, since I don't receive mails from EoFF at either my uni account or even my completely unfiltered home ISP account. I'd guess there's something about the way the server's configured to send that's wrong and everything is rejecting it, except, typically, Microsoft's broken implementation
Besides, even if it was marked as spam on Yahoo, we'd just see it filtered into our Bulk folders instead, it doesn't just vanish.