When someone sends a meeting request in iCalendar format from a POP/IMAP account in Microsoft Outlook to a non-Outlook user, the Content-Type:text/calendar information is not recognized. As a result, the message is not processed correctly.
Please try to do the following so that meeting request can be sent to non-Outlook user properly.
- Open Tools ->Options
- In the Preferences tab, click Calendar Options
- In the Calendar Options dialog box, under Advanced Options
Un-check the box When sending meeting requests over the Internet,
use iCalendar format.