what I used
Excmo. Sr. Leonel Fern?ndez
Presidente de la Republica
Palacio Nacional
Santo Domingo, Republica Dominicana
The e-mail address I'm not sure of and his web page still isn't functioning correctly (only been 100 days).
I sent a letter to him both by postal and e-mail on 4 Oct and haven't heard from anyone on his staff so I can't say that the postal address is any good either but worth a try. Good luck.