I was told a e-mail ddress from yahoo but I tried to contact this person and the e-mail keeps coming back?

i was in yahoo personals and i sent a flirt and ask them how they liked to be contacted because i didn't have the money to join to e-mail him so he gave me his id as rebel_iron_ride at yahoo mail so i tried it and put yahoo.com at the end and it came back as unknown address. i really liked this guy but i can't get in touch with him. does anyone know how to find out how i can get this address completed.