I received what I assume was a group message from my cousin (who uses a Galaxy S3 on sprint) but the contact number was formatted strangely. Let's assume my number is 555-1234-567 and his number is 555-8675-309. The contact number showed up as firstname.lastname@example.org .com. The message was also preceded by a "/"
When I open Google Voice, however, I see his proper contact name with his proper message (but no other recipient numbers). Of course, everyone who replied to the group message showed up in Hangouts in a similar fashion with their number in place of my cousin's, but in Google Voice they had their own separate thread with their proper contact name and message.
Is this just an issue with Google Voice and MMS? I assume the group message he sent was converted to MMS through the stock messaging app on the S3, but I'm not certain.