Consider the following scenario:
User A's mailbox is hosted by Microsoft Exchange Server 2016.
User B uses the Israel time zone, and sends User A a meeting request that has a customized .ics file added. The meeting request may be sent by using a Simple Mail Transfer Protocol (SMTP) tool, such as Telnet.
The .ics file may be generated manually by Exchange Server 2013 or by some third-party tools.
The .ics file contains both RDATE and RRULE properties for DAYLIGHT and STANDARD. You can open the .ics file by using a text editor, such as Notepad, to check the properties.
In this scenario, user A receives a meeting request that has a "not supported calendar message.ics" attachment.
This issue occurs because the VTIMEZONE parsing fails and the iCal parsing manner isn't correct.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology that Microsoft uses to describe software updates.
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.