The alleged crime took place at the house of the victim's in-laws at Sambhi village on August 2, 2012.
The letter alleged that the victim was abused when she was alone at home and the accused had threatened to kill if the matter was reported to anyone.
The police verified the complaint and contacted the victim whose medical examination was done after she was counselled by a team of women officials.
The police said the suspect, Rajesh, was arrested and would be produced in the court on Sunday.