Exchange external/Internet-bound automated response messages must be disabled.
Overview
Finding ID
Version
Rule ID
IA Controls
Severity
V-228392
EX16-MB-000480
SV-228392r879653_rule
Medium
Description
Spam originators, in an effort to refine mailing lists, sometimes monitor transmissions for automated bounce-back messages. Automated messages include such items as "Out of Office" responses, nondelivery messages, and automated message forwarding.
Automated bounce-back messages can be used by a third party to determine if users exist on the server. This can result in the disclosure of active user accounts to third parties, paving the way for possible future attacks.