Misconduct and Legal Action for Data Leakage
The sharing, leaking, or dissemination of company information through email or any other mode to outsiders by an employee constitutes misconduct. If you want to know whether there is a basis for taking legal action against an employee involved in an information or data leakage offense, the answer is yes. You can pursue legal action only when you have evidence of illegal activity. The use of email or sharing of information is not illegal unless you have a policy in place that defines it as such. To proceed with legal action, you must have proof of 'illegality' against the concerned individual.
Your establishment should have written policies and actions for the violation of these principles. If such policies are not in place, ask your management to draft one with the assistance of a lawyer.
Steps to Prevent Data Leakage
Does your establishment have its own email system? If so, block other pop-ups, implement filters, and monitor all outgoing emails. As an immediate step, obtain a fidelity guarantee from the employee you suspect to be the prime suspect.