Every cloud-based email service "scans your email" and does it a lot. This is mandatory in order to: - Junk filtering, fishing protection and other security pr

Every cloud-based email service "scans your email" and does it a lot. This is mandatory in order to: - Junk filtering, fishing protection and other security protections; all impossible to implement without deep scanning, analysis and correlation (this last item is important: some information extracted from your email is combined to information from other people's emails, in big statistical models and fancy machine learning jobs). - Index content so you can search it (unless you want to only be able to search by subject and other headers... no, 1988 called, wants its Eudora back). Bing.com may not include results from email, but this is irrelevant, Outlook.com certainly has full-text search so there's indexing. - Implement all kinds of cool stuff, e.g. Google Now right now shows that my last Amazon order has shipped, a single click on that shows the USPS tracking, how cool is that. Or more modestly, integration with other services from the same provider or from others such as cloud storage, office apps etc., or even simpler features like Outlook.com's ability to automatically sort email into categories, I doubt very much they can do it only looking at headers. (Even if they do, in many cases there's enough private info in headers that just not looking at the email body shouldn't reduce your paranoia.) In the big picture, the extra scanning for ad targeting is really a very minor part of the whole. So it all boils down to discussing whether you prefer targeted ads or untargeted ads, and whether you trust the cloud service to protect the private information used for this. Notice that this same potential issue exists for all functionality above, not just for ad targeting; so if you don't trust GMail as a matter of principle, then you shouldn't trust Outlook.com either.