Trellix Endpoint Security includes an option (enabled by default) to block all outbound connections over TCP port 25. This helps reduce the risk of a compromised host propagating a worm over SMTP using a homemade mail client.
Trellix Endpoint Security avoids blocking outbound SMTP connections from legitimate mail clients, such as Outlook and Eudora, by including the processes used by these products in an exclusion list. In other words, VirusScan ships with a list of processes it will allow to create outbound TCP port 25 connections; all other processes are denied that access.
The Manager takes advantage of the JavaMail API to send SMTP notifications. If you enable SMTP notification and also run Trellix Endpoint Security, you must add java.exe to the list of excluded processes. If you do not explicitly create the exclusion within VirusScan, you will see a Mailer Unreachable error in the Manager Operational Status to each time the Manager attempts to connect to its configured mail server.
To add the exclusion, append java.exe to the exclusion list of Trellix Endpoint Security On-Access Scan and On-Demand Scan.