From OpenStreetMap Wiki
Proxy vote stopped by Google spam filter
I got the following when I sent my proxy vote to the addresses in question:
Delivery to the following recipient failed permanently: firstname.lastname@example.org Technical details of permanent failure: Message rejected by Google Groups. Please visit http://mail.google.com/support/bin/answer.py?hl=en&answer=188131 to review our Bulk Email Sender Guidelines.