Google now allows people with an account on its Google Plus social network to email people even if that user does not know that user's address, creating a potential privacy vulnerability in its network that resembles a previous attempt to link Gmail with its failed social network Buzz.
Google product manager David Nachum announced the change in a company blog post on Thursday for its social network that has 540 million active users.
"Now it's easier for people using Gmail and Google+ to connect over email," Nachum said. "As an extension of some earlier improvements that keep Gmail contacts automatically up to date using Google+, Gmail will suggest your Google+ connections as recipients when you are composing a new email."
That means people without a Google Plus account are not affected, but those that have them could get a lot of unwanted emails, including from people they might be trying to avoid.
Users of Gmail will get an message from Google telling users when the change goes live and pointing them to privacy settings that will allow them to limit what Google Plus users are allowed to email them, or to opt out completely.
Google has made changes to its user privacy like this before with its previous social network, Google Buzz, which automatically synced the accounts of its Web services including email, resulting in a network that publicly showed who people emailed and chatted with most often. The Federal Trade Commission ruled in March 2011 that Google had violated the privacy of its users by creating Buzz with that user base.
The FTC decided that Google must in the future gain the consent of its users before including them in any new services or sharing their information in any new or unexpected ways, and required Google to conduct independent privacy audits through 2031. Google launched Google Plus in June 2011 and began shutting down its Buzz feature in October 2011.