We are a financial institution and every year we have an outside company come in and do a security assessment on our systems. A couple of the items that need remediation involve changing our SMTP banner that is permitting user enumeration and discloses our internal domain name. We are a Windows network (Server 03 and 08) running MDaemon as our email service. If any more information is needed, please let me know. We also utilize Cisco Ironport email and web gateway devices.