Outlook 2016 for Mac & Windows, Outlook apps for devices, Outlook on the web (both Exchange online and Outlook.com), and Windows 10 Mail and Calendar apps have summary cards for flight reservations and package delivery notifications.
This feature is not supported by all airlines or booking companies, but more are expected to be added in the future, along with hotel and rental car reservations. On the consumer side, dining reservations and entertainment events are added to the calendar.
In addition to detecting the events and adding them to your calendar, Outlook will display a summary of the upcoming event in the email confirmation in the form of a large summary card at the top. A very large summary card. Large enough that it blocks much of the actual email for many users.
If you don’t want these types of events added to your calendar, you can disable it in Outlook on the web, in Calendar Options, under Events from email. This setting doesn’t appear to affect summary cards.
For more information and screenshots, see Stay on top of your travel and deliveries with Outlook