Why Email Providers Scan Your Emails (consumerreports.org)

Google stopped scanning emails for ad personalization a couple years ago, but it still scans email for other services it provides (like how the mobile app will tell you of an upcoming appointment or flight). There’s no way to disable this. It’s in their terms of service that they will do this.

When I look in my spam folder, I am always pleasantly surprised at how effective my ISP is in spam detection.