I recently acquired this cover with an 1863 2c black Jackson (Scott 73) postmarked New Haven, CT on 6 January (1867).
Although the stamp's centering was poor and there was a piece missing at upper right, I still wanted to add the cover to my collection because the addressee, Simeon Eben Baldwin, was a fairly prominent American.

I imagine the docketing on the reverse is in Baldwin's hand -- any thoughts on the name of the sender would be appreciated.

Here is a short biography on Baldwin from the National Governors Association.
Quote:
SIMEON EBEN BALDWIN, Connecticut's 48th governor and son of Connecticut Governor Roger Sherman Baldwin (1844-1846), was born in New Haven, Connecticut, on February 5, 1840. He graduated from Yale University in 1861, studied law at Harvard and Yale, and was admitted to the bar in 1863. Baldwin taught at Yale from 1869 to 1919, retiring in 1919 as professor emeritus. He authored numerous articles, pamphlets, and books. In 1878 he cofounded the American Bar Association, serving as its president in 1890, and he was president of the Association of American Law Schools in 1902. Baldwin served on the Connecticut State Supreme Court from 1897 to 1910, serving as chief justice from 1907 to 1910. He won the 1910 Democratic gubernatorial nomination, and was elected Governor of Connecticut. He was reelected to a second term in 1912. During his tenure, the Corrupt Practices Act was passed, as well as a civil service law that installed a merit system for state employees. A public utilities commission was founded, and a workmen's compensation bill was enacted that held employers responsible for accidents incurred at work. Baldwin left the governor's office on January 6, 1915, and returned to teaching at Yale. Governor Simeon E. Baldwin died on January 30, 1927, and is buried at the Grove Street Cemetery in New Haven.
Sources:
Sobel, Robert, and John Raimo, eds. Biographical Directory of the Governors of the United States, 1789-1978, Vol. 1, Westport, Conn.; Meckler Books, 1978. 4 vols.