Starting tomorrow, June 3, Yahoo! is discontinuing its Mail Classic and at the same time forcing Mail users to accept the Communications Terms of Service and Privacy Policy of the new version that allows the company to scan your emails to “deliver product features, relevant advertising, and abuse protection.”
While you can opt out of the targeted ads, you won’t be free from the scanning. Yahoo! says you can use a desktop email client but need to agree with their terms or ditch Yahoo! Mail altogether. You can read up about these changes over here.