This was answered recently on the forum.
http://developer.cisco.com/web/cvp/forums/-/message_boards/view_message/5881522

You'll have to write some custom java that executes at the End Of Call - which means it executes no matter how the call flow ends. You can determine how the call ended (eg, hangup) and send the email then.

If the caller hungup while recording the recording might not have gotten stored on the local drive, or wherever you are specifiying the recording be stored. You could check the path where you expect to find the file in your endcall class you are writing, if you find the file you can attach it. You are going to have to get the file name from somewhere, not sure what you are using for the file name but you'll have to reference it as element or session data in your endcall class to see if it exists. I

f the call ends your Studio app is done so you can't use the sendmail element, you have to use that referenced article Janine gave to get the java code to send an email, I use javax for it, pretty simple and google will produce lots of other methods. If the file exists you can attach it in the endcall class.

Bill Westby.