You would like to configure the Enforce Server to use SMTP over TLS to send out notifications and alerts.
Unsupported Versions
DLP 16.0.x
DLP 15.8
Supported Versions
DLP 16.1
Data Loss Prevention versions 16.0.x and 15.8.x currently support only non-TLS SMTP for sending reports and alerts from the Enforce Server.
Support for SMTP over TLS for Enforce notifications is available in version 16.1.
Workaround for DLP 15.8 and 16.0: The DLP administrator can configure the Enforce Server to use a non-TLS SMTP server in DLP (under System → Settings → General) and set up this SMTP server to relay messages to a TLS-enabled SMTP server for further delivery.
Configuration and troubleshooting of SMTP relay issues is outside the DLP support scope.