Apparently it can in Australia,
A Queensland court has accepted a dead man’s unsent, draft text message leaving his possessions to his brother and nephew instead of his wife and son, as an official will.
. . .
The unsent message detailed how to access the man’s bank account details and where he wanted his ashes to be buried.
“You and [nephew] keep all that I have house and superannuation, put my ashes in the back garden … [wife] will take her stuff only she’s ok gone back to her ex AGAIN I’m beaten. A bit of cash behind TV and a bit in the bank Cash card pin … My will”