Letter to Larry Merlo, President and CEO of CVS Health, Tim Wentworth, President of Express Scripts and Cigna Services, Steven Anderson, President and CEO of the National Association of Chain Drug Stores, John Prince, CEO of OptumRx, JC Scott, President and CEO of Pharmaceutical Care Management Association, Heyward Donigan, President and CEO of Rite Aid Corp., and Alex Gourlay, Co-Chief Operating Officer of Algreens Boots Alliance, Inc,, and President of Walgreens - E&C Leaders Officially Launch Investigation into Impact of Postal Service Changes on Prescription Drug Deliveries