I blame Luke himself.
...wait what?! It's google groups, bro
If you get malicious email as a result of posting to any email list
then I suggest you improve your junk email filter. I believe it's
not the job of the list maintainer to "protect" email addresses
unless the maintainer claims up from that postings will be
anonymous.
Cordially,
Jon Forrest
Seriously, it is Google Groups, so you get the protection it offers, requiring logins and CAPTCHA to view full email addresses on the web archives, etc etc, but it's difficult to stop people subscribing to lists and collecting addresses that way.