Which solution should Justin consider to prevent employees from sending sensitive information to personal email?

Justin should consider a Data Loss Prevention (DLP) solution to prevent employees from sending sensitive information to personal email. DLP systems are specifically designed to monitor and control data transfers, ensuring that sensitive data does not leave the organization's network without proper authorization. This technology can analyze content moving through email, file transfers, and other channels, detecting sensitive information based on predefined policies. When a violation of these policies is detected, DLP can either block the transmission, alert administrators, or take other pre-defined actions to mitigate potential data leaks.

Using a firewall would not directly prevent employees from sending sensitive information to personal emails, as firewalls primarily monitor and filter incoming and outgoing network traffic based on predetermined security rules without specific focus on the content being sent. While encryption is essential for protecting data both in transit and at rest, it does not prevent the action of sending sensitive information; rather, it secures the data being transferred. Access Control Lists (ACLs) can restrict what resources users can access on a network, but they do not provide the granular control needed to prevent specific types of data, like sensitive information, from being sent to personal email accounts. Therefore, DLP stands out as the most appropriate solution for controlling the unauthorized transmission of sensitive data.