Not really a problem with email. It's more a series of critical errors on the part of the Google Groups system. If they were to implement Gmail-quality spam filtering then most of my concerns would be moot (since I never would have had to turn on moderation and these sketchy spoofers would've been caught right at the gate).
This is odd - Sender Policy Framework was instituted to stop spoofing, & Gmail actually uses it. So allowing Gmail spoofers is bypassing the spam filters & SPF.
http://jquery.markmail.org/ seems to have a good chunk of the lists archived. They can probably get you a copy (marked up in XML) if you ask - that might be better than scraping.
