It's Yr Life by Tempany Deckert and Tristan Bancks

Random House Australia 2009.
(Age range: 14 - 16). Recommended. Two students from opposite sides of the world are forced to email each other for a year 10 English assignment. Milla lives in Hollywood with all the trappings of a successful family. Sims is a street kid living in Byron Bay in a foster home. Neither are keen on the idea of the assignment, however as they begin to correspond they find a link developing and soon they are dependent on each other as they try and solve the mysteries they both find creeping into their lives.
Milla discovers footprints outside her bedroom window and is anxious to know who they belong to and why the person is sneeking around her home. Sims discovers body parts in a bag whilst searching for food in a local supermarket dumpster. Unsure whether to go to the police or whether one of his house mates is involved he confides in Milla to try and decide what best to do.
The communication between the characters, written in true email teenage speak adds to the suspense of the story. Often short and to the point, other times detailed and full of information, as the characters try and support each other through the trials of their lives.
Tempany Deckert and Tristan Bancks communicated solely by email to compile this novel giving it an authenticity that helps the reader to stay engaged with the storyline and compelled to continue reading to ensure the issues facing Milla and Sims are resolved.
Tracy Glover