How can I allow HTTPS traffic on Forefront server

I have installed Forefront 2010 and added a rule to allow ALL Outbound traffic of any type to the external network as a test. It works OK for http traffic but blocks everything https. Can anyone help me understand why this is? There is no specific rule to block https apart from the default Deny that blocks any traffic not specifically allowed.

Click for image of rules setup

For Google this is the log that is recorded:

Status: 12202 Forefront TGM denied the specified Uniform Resource Locator

Image of log for blocked Google access