Gmail Now Lets You Email Your Google+ Connections
thenextweb.com
thenextweb.com
I wonder how it interacts with "undo send" …
It's not "until you send", but "until you receive a reply".
That's not what the article says. It says that it hides your email address until you send the connection an email (and, conversely, hides the connections email address until they send you an email):
Quote: The good news is that your email address isn’t visible to a Google+ connection unless you send him or her an email. The reverse is also true: his or her email address isn’t visible to you unless he or she sends you an email.
"Anyone on Google+", "Extended Circles", "Circles", and "No One".
http://www.theguardian.com/technology/2014/jan/07/google-han...