The message reportedly shows a non-white man being tortured. Officers being investigated could face dismissal for circulating it on police computers.
The Victoria police force has been criticised for failing to respond adequately to a series of attacks against Indian students in Melbourne.
Earlier this month the police chief admitted some officers were racist.
Computer experts tracking the e-mail found that several had added racist comments before forwarding it on to colleagues, the Melbourne newspaper The Age reports.
It was one of a series of e-mails that were either racist or pornographic in nature, according to the Victoria Police chief Simon Overland.
"It's offensive and my view is that it would cause significant concern and alarm in the community if the nature of the material was made public," he said.
Earlier this month, Mr Overland was forced to concede there were racial bigots within the ranks of his force.
This followed a damning report that accused police officers of taunting and beating up an African youth.
BBC News
