A mail-tracking feature is a mailbox or hosting function that records, traces, or reports email delivery activity. It may log message status, generate delivery reports, inspect headers, or store tracking data for later review. By itself, that is a normal administrative capability.
In cyber security, the feature matters because it can touch sensitive system resources such as files, logs, queues, or command handlers. If input validation or privilege boundaries are weak, a tracing function may become a path for file creation, information disclosure, or even code execution. Attackers look for these mistakes in hosted email systems because they often begin with a valid account and then abuse a trusted feature to reach deeper privileges. Defenders reduce the risk by limiting who can use tracking functions, isolating file operations, validating all mail metadata, and monitoring for unusual writes or process activity around mail services.