Let's face it,
No matter how ingenious the paperless idea --- unless employees are rewarded for compliance --- Joe Q. Government will continue to print out his emails...
So, reward good old Joe Q.'s paperless compliance with promotion points.
Track Joe G’s printing --- i.e. every time he prints, his "print number" goes up. During employee evaluations, this “print number” is scored and used as a criteria for evaluation. i.e. the lower the number, the higher the employee rating.
If good old Joe Q realizes that he can get promotoed for observing the paperless standard, then all employees will get creative.