It's always been possible for a complete stranger to email you via the internet. But it was impossible without one thing: your email address.
Google appears to be keen to put a stop to that nuisance, however, introducing a new feature which will allow absolutely anyone on Google+ to email you, regardless of whether they actually know your email address.
The new feature, which some will undoubtedly find disturbing, was announced on the Gmail blog:
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. 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.
Fortunately, this new service isn't a a complete and utter privacy disaster. Google says it won't display your Gmail address to these strangers, and they won't discover your email address unless you reply to them.
Furthermore, these strangers won't be able to enter an ongoing email conversation with you unless you respond to them, or add them to your Google+ Circles.
Nonetheless, it's likely that this new "feature" won't be welcomed by all. It's easy to imagine, for instance, how it could be used by people who were violent to send upsetting messages to a former spouse or domestic partner who has tried to create a new life away from physical abuse. It's also easy to picture public figures receiving a torrent of unwelcome messages in their inbox from fans or obsessive individuals.
Typically, however, Google has assumed that this feature will be wanted by most of its users - and so will be enabling it by default.
If you don't want complete strangers who don't know your email address to send you emails, you will need to make an adjust to a new setting being rolled out in Gmail - "Email via Google+".
The choices, which range from "Anyone on Google+" to "No one", allow you to restrict who can send you an email via Google+. If you don't see the option yet, it's probably because Google hasn't finished rolling out this "feature" yet.
Google says that all users would be alerted to the new feature and how to change the default setting, within the next few days.
It is a nuisance how internet companies change settings like this, pulling the rug from underneath individuals who were happy with the status quo and don't want to have to constantly check that they aren't a little less private this week than they were last week.
And let's not forget - there are more people with Gmail accounts than ever before, with the need these days to have a Google account to get the most out of YouTube or an Android phone.
If you don't have enough friends already on Google+, please feel free to include me in your circles and I'll do my best to keep you up-to-date with security news.
I can't promise that I'll reply to every email though...