Today, Outlook.com launched "Don't Get Scroogled by Gmail," a campaign against rival's Google email service, aimed "to educate Americans about Google?s practice of going through the contents of all Gmail emails to sell and target ads," according to Microsoft.

Microsoft accuses Google of routinely engaging in the practice of reading through users' personal email to sell ads - something that Microsoft claims Outlook.com doesn't do.

Microsoft also encourages users to sign the petition at Scroogled.com and tell Google to stop going through their emails to sell ads.

Microsoft claims that Google even goes through emails from non-Gmail users to generate advertising income. "Gmail goes through all incoming email messages, from any email provider, and sells ads based on the content of those emails," Microsoft says.

Google does not enable Gmail users to opt out of seeing ads based on the content of emails.

Microsoft also presented the resulys of GfK Roper poll, commissioned by Microsoft. The poll showed that only 30 percent of Americans are aware that any email service goes through the content of personal emails to sell ads, and 88 percent of consumers disapprove of this practice.

Beginning today and continuing for the next few weeks, the Outlook.com-sponsored "Don't Get Scroogled" activities will appear online and offline.