McAfee GroupShield for Microsoft Exchange on Exchange Server 2000, and possibly other anti-virus or anti-spam products from McAfee or other vendors, does not scan X- headers for malicious content, which allows remote attackers to bypass virus detection via a crafted message, as demonstrated by a message with an X-Testing header and no message body.
Prioritise with Active Threat Intelligence
With curated Threat Intelligence, you can see which vulnerabilities truly put you at risk, prioritize what matters most, and act before attackers do.
Explore Intelligence Hub