A mail carrier in New Hampshire accused of assaulting children in his official postal van has been sentenced to a year in jail with all but one month suspended after pleading guilty to one count of simple assault. Six other charges of aggravated felonious sexual assault were dropped against Frank Saucier of Tyngsborough, Mass. Saucier was sentenced Monday in Manchester. He was arrested last year, when Manchester police said he let several children into his postal van to ‘‘play house,’’ and allegedly spanked a 10-year-old boy. Saucier’s route was on Manchester’s west side.