Microsoft Office – why are the email options disabled?
If you’re using Microsoft Office but find that the email options are disabled, this is most likely because Outlook is not installed.
To work around this without installing Outlook, please see “method 2″ in the following Microsoft Knowledgebase article:
NB: if you have a 64-bit machine and are running a 32-bit version of Office, you need to ensure that you're editing the following registry key (in contrast to what "method 2" says in the above link):
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows Messaging Subsystem