SAN FRANCISCO -- Privacy advocates are raising the alarm about a new feature in Google's email service Gmail that lets Google+ users send you emails even if they don't know your email address.
Google said Thursday that it has broadened Gmail contacts to include Google+ contacts.
"Have you ever started typing an email to someone only to realize halfway through the draft that you haven't actually exchanged email addresses? If you are nodding your head 'yes' and already have a Google+ profile, then you're in luck, because now it's easier for people using Gmail and Google+ to connect over email," Google product manager David Nachum wrote in a blog post. "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."
Your email address isn't visible to a Google+ connection unless you send that person an email, and that person's email address isn't visible to you unless he or she sends you an email, Google says.
The new feature is part of a broader effort to commingle Google+ with Google's other services. The 2 1/2-year-old social network has 540 million active users. When people sign up for Gmail, they now automatically receive a Google+ account.
Google said that if users do not wish to receive email messages via their Google+ profiles, they can change their settings.
To opt out, go to your Gmail settings (click the gear in the top right corner of your inbox and then choose "Settings" from the drop-down menu). Scroll down to "Email via Google+" which asks the question, "Who can email you via your Google+ profile?" Change the answer to "No one." Then scroll down to the bottom of the Settings list and click "Save Changes."
If you'd like some but not all Google+ users to be able to email you, you can instead choose "Circles" (only the people you know) or "Extended circles" (only the people you know and the people they know).
Emails from strangers will land in a special inbox that is separate from messages from friends. If the recipient does not reply to the message, Gmail will block future messages.
Privacy advocates say Google should have made the new feature "opt in," meaning that users would have to sign up to receive messages from Google+ users, rather than turning on the feature for everyone. Businesses and celebrities will not have the feature automatically turned on.
Gmail users began receiving emails about the new feature Thursday.
Marc Rotenberg, executive director of the Electronic Privacy Information Center, said the feature was "eerily similar to the Buzz fiasco, when Google tried to force Gmail users into Google's social network service Buzz," violating their privacy.
Google reached a settlement with the Federal Trade Commission over Buzz that called for Google to ask users before sharing their data with outsiders. The settlement required Google to submit to independent privacy audits for 20 years.
"The FTC needs to determine whether this change to Google's business practices violates the consent order that resulted from the Buzz investigation," Rotenberg said.