Responding to complaints that it reads users' emails and then generates targeted advertisements, Google this week issued a new Terms of Service (TOS) document for its online services. The document clearly states that Google does indeed read users' emails and then generates targeted advertisements. The only surprise is that it does so much more frequently than previously expected.

Related: Microsoft Highlights Gmail's Spam Delivery Intrusion in New Scroogled Ad

This shouldn't be all that surprising. After all, with over 90 percent of its annual revenues coming from advertising, Google has obviously developed some skills in this area. But the news will likely be disheartening for those who believe that Google's scanning of email is somehow no different than the activities undertaken by other email providers.

Google's email scanning activities were publicized—shocker—by Microsoft, which as part of its successful "Scroogled" advertising efforts noted that its own email service, Outlook.com, does not violate user privacy.

Related: Scroogled: Microsoft Takes Google to Task for Privacy Violations

"Google goes through every Gmail that's sent or received, looking for keywords so they can target Gmail users with paid ads," Microsoft claimed. "And there's no way to opt out of this invasion of your privacy."

Both of those claims are correct, as a revised Google services TOS shows.

"Our automated systems analyze your content (including emails) to provide you personally relevant product features, such as customized search results, tailored advertising, and spam and malware detection," a new part of the TOS reads. "This analysis occurs as the content is sent, received, and when it is stored."

When the email is sent. When it is received. And while it is stored on Google's servers. There is no way to opt out of this behavior.

Other email services, like Microsoft's Outlook.com, do scan your email, but they do so only to prevent spam and malware. And although the free version of Outlook.com offers a paid upgrade that removes the text-based ads provided by that services, there's no similar offering for Gmail. Even those that pay for Google Apps are still subjected to Google's email scanning practices, all to further the aims of Google's advertising prowess. Again, you cannot opt out of this practice even if you pay for the service.

Google changed its TOS in the wake of the Scroogled campaign, which triggered several lawsuits accusing Google of violating both federal and state privacy and wiretapping laws. The firm previously stated that users had "implicitly" agreed to this scanning when they signed up for Gmail.

"[These TOS changes] will give people even greater clarity and are based on feedback we've received over the last few months," a Google spokesperson said.