Where exactly do we place a mezuzah? The obligation to perform the mitzvah of Mezuzah is mandatory on all the doorposts of one's home and place of business with a few exceptions to be enumerated later. It is attached to the upper third (but not less than four inches from the top) of a doorpost to the right as one enters a room. Ashkenazi Jews place them at a slant toward the interior of the room and Sephardic Jews place them vertically straight up and down. One should follow the custom of one's family.