Rinse the chicken with cold water and pat dry with paper towels. Place the chicken in a large baking dish and season lightly with salt. Cover with plastic wrap and refrigerate for at least 1 hour or up to overnight.
In a bowl, whisk together the flour, the 2 1/2 teaspoons salt, the black pepper, paprika, cayenne pepper and marjoram. Divide the flour mixture evenly between 2 bowls. Pour the buttermilk into another bowl.
In a 6 quart deep saute pan over medium heat, heat the oil to 375 degrees F. or 190 degrees Celsius on a deep frying thermometer.
Pat the chicken with paper towels to remove excess moisture. Dip the chicken into the flour, coating the pieces evenly, and shake off the excess flour. Dip the chicken into the buttermilk, allowing the excess to drip off, then dip the pieces into the other bowl of flour and shake off the excess. Place the chicken on a baking sheet. Line another sheet with paper towels.
Using tongs and working in batches, carefully place the chicken in the oil; do not overcrowd the pan. Fry the chicken until the underside is golden brown, about 10 minutes. Turn the pieces over and fry until the chicken is opaque throughout, 10-12 minutes more; an instant read thermometer inserted into the breasts should register 160 degrees F. or 71 degrees Celsius and into the legs and thighs it should read 170 degrees F. and 77 degrees Celsius
Using tongs, transfer the chicken to the paper towel lined baking sheet. Let cool there for 5 minutes, then serve.