Not supported calendar message – possible reasons and solutions

With the Calendar E-Mail Extension you can organize meetings in a SharePoint Calendar and invite attendees directly from SharePoint via e-mail meeting requests. If your attendees receive an email with an attachment “not supported calendar message.ics” instead of a valid meeting request, it is possible that something is configured incorrectly in your Exchange or that your aren’t using the latest version of the Calendar E-Mail Extension.

Not supported calendar message

This is what it should look like:

Valid meeting request

Possible reasons for the “not supported calendar message” are:

Meeting requests are forwarded by a transport rule

Meeting requests are forwarded from Exchange by a transport rule or you have configured an e-mail contact by which invites are forwarded. If you use a transport rule, you must redirect the message – this replaces the recipient. When Exchange forwards a meeting request, it encapsulates the original message, this leads to a “not supported calendar message.ics”.

Your SharePoint Site is in a time zone without daylight saving time

This is fixed since 2/27/14.

In our previous version we always included a rule for daylight saving changes to support the organization of meetings in different time zones and recurring meetings that overlap time changes. However, this resulted in a “not supported calendar message.ics” message if the site is in a time zone without daylight saving changes and the recipient is in the same time zone.

If both reasons do not apply to your situation, but you still receive the “not supported calendar message”, please send an e-mail to Please also let us know if you receive the “broken” message all the time or only for certain events, for example only if you use some specific recurrence patterns.

If you use our Employee Training Management and attendees also receive an “not supported calendar message” when they enroll in a training, you can also use the solutions described above.