A Delta Air Lines Boeing 767-300ER, N185DN, operating as Delta flight 266, was taxiing on taxiway B for departure on runway 04 at Boston Logan International Airport (BOS), when its left winglet struck the horizontal stabilizer of an Atlantic Southeast Airlines CRJ900, N132EV, operating as ASA flight 4904, which was number three in line on taxiway M waiting for departure on runway 09. As the Boeing 767 approached and passed the intersection with taxiway M, the left winglet of the B767 struck the horizontal tail of the CRJ900. The CRJ900 sustained substantial damage, which included damage to the horizontal tail and vertical tail; the airplane lost fluid in all three hydraulic systems. Parts of the B767 winglet were sheared off and embedded in the tail of the CRJ900. The passengers on the CRJ900 were deplaned on the taxiway, and the B767 taxied back to the terminal. PROBABLE CAUSE: “The B767 Captain’s failure to maintain a safe clearance between his wing and the tail of the CRJ900 that was stopped on a taxiway.”