If you are a Yahoo! Mail user and you just got a notice that you would have to upgrade your Yahoo! email, please realize that this means that Yahoo will now be scanning your email to deliver advertising.
Last week Yahoo forced all their email users to switch to their new version of Mail. It’s not the changes in the mail program’s capabilities that you should know about, it is the fact that if you continue using Yahoo! mail, Yahoo will now scan your email to “deliver product features, relevant advertising, and abuse protection”.
Yahoo has stated unequivocally that if you don’t like this new policy, you will have to look for another email service.
Just for comparison, though, many other services do the same thing. Gmail has targeted users for ads since its inception. Also, websites are now sharing similar information.
Read more about what they do with the advertising information they gather. Read this.