A booming mortgage market has also increased the spoils for the subservicing industry. GMAC Mortgage Corporation’s subservicing volume grew by 45 percent from the second to third quarter of this year, hitting $32.5 billion. “We are experiencing tremendous growth,” said Tom Donatacci, GMAC Mortgage Corp.’s senior VP of business development. He attributed the gain to growth in the overall subservicing market, and to GMAC’s subservicing breadth and flexibility. …