Mail Security 7.0 on Windows Server 2012 - ASP.NET?

Hello,

I'm getting tired of the following problem, as there is no solution to be found anywhere. Can't imagine that I'm the other person with this problem but anyway.

I'm trying to install Symantec Mail Security for Microsoft Exchange 7.0 on a Windows 2012 Server with Exchange 2013. However, during the installation (which is started correctly with setup.exe, not the .msi), I am informed that I need to install "ASP.NET Web Extension 2.0". That's a great information as NO documentation or guide tells me how to install this...

Any help would be really appreciated.

Rgds,
Chris