Tracebacks are recorded when they arise from certain actions, including all tracebacks caused by a command, and all tracebacks during creation and destruction of an object. The traceback is stored along with relevant information on the administrator-only mail list *tracebacks (limited to administrators because it may contain privileged information, such as commands typed by users).
To receive notification of the tracebacks as they occur, make sure to subscribe to the *tracebacks mailing list.
Whether a user see's tracebacks or not depends upon what their user class is, in relation to the system setting:
$sys:traceback-for
Which is a user class specifying what classes will see real tracebacks. If the user is not a descendant of this class, they will instead receive a polite message about the error.
Admin Commands | Traceback Recording