Shock Shop:You Have Ghost Mail (HB) by Terence Blacker

Spooky or funny, surprising or frightening, SHOCK SHOP is a collection of brand-new novels by some of the greatest names in children's writing. YOU HAVE GHOST-MAIL When Matthew Bourne gets his own computer he can't wait to start emailing his best friend Angie. But the expansion of the Internet has disturbed the spirit zone and a spooky message on Matthew's computer screen leads him to contact Giles, a boy who died fifty years ago. This ghostly friend desperately needs to contact his mother and Matthew is the only one who can help him. But danger is never far away when the living meet the dead...A paranormal adventure with a startling twist.