Disable Email Search in Spotlight to Avoid Message Tracking
A bug in Spotlight OS X Yosemite search can reveal personal information if you are an Apple Mail user. The bug exposes your IP address and other system data to spammers and other online tracking companies.
When you use Spotlight to search for an email, Spotlight shows a preview of it. When it does, it automatically opens external images that are referenced in the HTML email. These emails may include tracking pixels , which may reveal certain information about your system to spammers. In Infoworld tests, they were able to send a tracking pixel and collect the IP address, current OS version, and some browser information.
Spotlight does this even if you’ve turned off the “download deleted content to message” option in Mail. The crash seems to only affect Apple Mail users, so if you’re using a third party app or web service you’re fine. For now, the only way to prevent this is to turn off Spotlight search for mail. Go to System Preferences> Spotlight and uncheck the Mail & Messages box.
OS X Search Failure May Reveal Personal Information of Apple Mail Users | InfoWorld