I believe the E. E. Cummings Copyright Trust (or estate) is handled by the Liveright Publishing Corporation. You can contract Liveright Publishing at the address below. I have included other information that might be helpful. Liveright Publishing is currently a division of W. W. Norton & Company.
Liveright Publishing Corporation,
500 5th Avenue,
New York, New York 10110-0002
Liveright Publishing was named after its founder, Horace Liveright (1885-1933). He founded The Modern Library publishing house and Liveright was the first publisher of books by Ernest Hemingway and William Faulkner.