Viewing Outlook Calendar Events in Thunderbird
vCalendar is a computer file format that allows users to share meeting requests and calendar events. The new version is based on vCalendar but named iCalendar instead and usually has the file extension ics. Outlook.com and the traditional Outlook program in Windows allows to share events and calendar requests with any other contact but sometimes when you share the calendar events with users who have other email client they will get a raw message instead.
In Thunderbird for example when you get a .ics file from someone who sent you a calendar event then you will see the raw message unless you get a calendar extension.
Viewing Outlook Calendar Events in Thunderbird
In order to view Outlook calendar events in Thunderbird you can install Lighting extension. Once you install this extension you will see a calendar pane and after restarting Thunderbird the event will look better:
Once you have installed this extension, you can also integrate the calendar and events with Google Calendars, but you will need another extension named Provider for Google Calendar in order to make it work.
Learn more about iCalendar.