MS Outlook 2010 Either there is no default email

You see this error "Either there is no default email or the current mail client cannot fulfill the messaging requests" most likely your Outlook registry information is corrupted.

The good news, it is easy to fix this issue. Open regedit program (Note, it is not recommended to use this tool if you are not a technician or system engineer).

HKEY_LOCAL_MACHINE\Software\Clients\Mail\Microsoft Outlook

I highly recommend that you use the Microsoft Fix it tool, to automatically fix it for you.
Here's the link for detailed information.

Well, in this case this is not fully automatic. After you run the Microsoft Fix it, you need to manually repair your MS Office 2010 programs. Here's how to do it.

Click Start, click Control Panel, click Programs and Features, select Microsoft Office 2010 and then click Change button. Next, click Repair, and then click Continue. It will take 5-10 minutes to complete.

References:
http://support.microsoft.com/kb/813745
http://www.whaddya.com