In VA, unused vacation only has to be paid out if there is a policy of paying it out. You are free to consult with an attorney to see if the email will be considered a contract, but I wouldn't hold my breath on it. If the handbook says that the decision is to be made by senior management on the last day, then that's the deal.

Now, I will go on record as saying that's a foolish policy that has the potential to get the employer in trouble someday. But it's not an illegal policy and nothing you have posted suggests that failure to pay your vacation out has any liability for the employer this time.