The era of Yahoo CEO Marissa Mayer, seems to be in full swing. First, the acquisition of Tumblr, now Yahoo email account users are going to have the company, or rather, potential advertisers peeking into their subject lines and correspondence. It appears Mayer, a former Google employee, is taking the Gmail model and putting a Yahoo spin on it.

As with most news in the technology realm, this one touches on privacy issues. Those already have a Gmail account, are familiar with the ads. Driven and fed by the content in a user’s inbox, the service is a prime platform for advertisers. . For some, this is a hotbed issue because of the invasion, the systematic erosion of privacy that’s inherent in anyone – even a computer – having access to a person’s e-mail.

Bloomberg Businessweek reports that Mayer played a major role at Gmail, and has singled out Yahoo’s mail service as an early target when she became Yahoo’s chief executive. It scans and analyzes incoming and outgoing communications, including instant messages and SMS chats. As a result, Yahoo’s email service is about to include a bunch of targeted ads.

While the setup has to some extent become the norm throughout the industry, at least some businesses are crying foul. Business Insider reports the British Internet service BT is in the process of switching its six million customers from Yahoo. Some, however, has noted that the policy remains, to some degree, unchanged. In fact, it goes back to Yahoo Mail terms of services adopted in 2011, and since then Yahoo Mail users have agreed to have their emails scanned and certain advertising targeted towards them.

The change is likely to increase the competition between Google, Yahoo, and Microsoft — all of whom are competing for email dominance. Microsoft, which announced changes to its Hotmail email system in 2012, has sought to rebrand itself as users spent many of the last several years flocking to Gmail.