a world without google

the "Google Ads" or "Sponsored Links" or whatever they call them, will be directly related to the content of my most recent email correspondence.

Google AdWords use JavaScript and run locally on YOUR computer. This means that the JavaScript fetches ads based on a quick sweep of the text cached on the currently viewed page, based on frequency, so if the email says "cars" a bunch, then the ads will be related to cars, because the JavaScript then connects to Google's ad server and tells it "I want ads about cars." A simplified example, but again your computer is doing all the heavy lifting and Google is not "screen reading" your email themselves.
 
Again, if you're concerned about this stuff... GPG. You can also block off domains (like their ad providers) manually if your browser doesn't suck.

Jeff