I just don’t see that the furor over Gmail scanning email to place ads as justified.
First, Google is offering us something of value (free email, huge storage) in return for the service. If you don’t want your email scanned, then don’t use Gmail.
Second, Google has a track record of - well - trying to be a good citizen. With a bit of care Google can make sure that the auto-placed ads don’t automatically return too much information to marketers.
Third, who said email was private? As long as the FBI’s “Carnivore” program exists, you should assume that all your email is scanned.