Cortana was designed in many ways to mimic a personal assistant in Windows. Just say “Hey Cortana” and she’ll respond with an answer to a question, or carry out any number of functions for you. Well today she’s going to start scanning your emails in order to create helpful reminders in your calendar.
Any good assistant that has access to your business email would probably also want to put your scheduled appointments in your calendar. I say “probably” because I’ve obviously never had an assistant, and am just going off of what people do in the movies. Of course, Cortana will need your permission to actually add the appointment, as she can’t tell the difference between important meetings, and casual conversations that don’t need appointments.
If you’re worried about Microsoft snooping through your email, you’ll be a little relieved to know that the scan for time-related keywords only happens locally on your computer. The only time any information is uploaded to the cloud is when you confirm the creation of an appointment, and it gets synced to your other devices.
And for those that don’t like the thought of some tarted up holographic assistant snooping through your emails, you can disable this new feature entirely, without turning off all of Cortana’s functions. The feature is currently only available in the “insider” builds of the OS, though it will likely be rolled out to other users soon.