With respect, KOT, you need to read the op's post more carefully. The OP is launching a new message from Mail, not from Contacts. Mavericks has crippled the integration between Mail -> Contacts. In all previous versions, double-clicking or Drag-Drop from an individual contact or group into an address field in Mail has worked well. Not now. In my testing, the only integration possible is to begin typing in an address field (To:, CC:, BCC:), select the suggestion from the drop down menu, and click the little "+" button way over on the right.