A federal judge has sentenced a man to 25 years in prison for mailing a fatal dose of cyanide to a suicidal Englishman.Sidney Kilmartin's sentencing took place Tuesday in U.S. District Court in Portland. Kilmartin was charged with sending cyanide to Andrew Denton of Hull, England. He also was charged with advertising and mailing a substance he said was cyanide to several suicidal people. It was really Epsom salt.Kilmartin sent the real thing to Denton after Denton had threatened to report the fraud.The 56-year-old Kilmartin faced a maximum sentence of life in prison. His defense attorney said a fair sentence would range from zero to 20 years because of Kilmartin's history of mental illness.Kilmartin, of Windham, Maine, was arrested in 2014 and found guilty in 2016.