Hi Massimo,
I was having this trouble also, so I decided to start looking into it. In order for OS X to launch an application, it uses LaunchServices.
You can view the contents of the LaunchServices database by calling lsregister -dump from the following directory:
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.fram ework/Versions/A/Support
LaunchServices keeps a database of Uniform Type Identifiers (UTI) and uses these to open applications based on what the application claims to conform to. It appears that Microsoft Outlook 2011 does not conform to the following UTI's that Mail.app does conform to:
--------------------------------------------------------
service id: 776
menu: Mail/New Email With Selection
key:
port: Mail
message: mailSelection
user data:
timeout: -1
send types: "NSRTFDPboardType", "NSRTFPboardType", "NSStringPboardType", "Apple Web Archive pasteboard type"
return types:
--------------------------------------------------------
service id: 864
menu: Mail/New Email With Attachment
key:
port: Mail
message: mailDocument
user data:
timeout: -1
send types: "NSFilenamesPboardType"
return types:
--------------------------------------------------------
service id: 908
menu: Mail/New Email To Address
key:
port: Mail
message: mailTo
user data:
timeout: -1
send types: "NSStringPboardType"
return types:
Further, you can see the Services for each application in System Preferences:
If you would like Microsoft to support this in future perhaps a feature request might help:
http://www.microsoft.com/mac/product-feedback
-b