Xeams: Unauthenticated Root RCE via SMTP X-SM_SAVE_BODY_4DEBUGGING Arbitrary File Write

Xeams 10.3 build 6449 lets an attacker write arbitrary files to any path by setting the X-SM_SAVE_BODY_4DEBUGGING MIME header on an inbound SMTP message — no auth, no HTTP, no license. When Xeams runs as root, writing a job into /etc/cron.d/ yields unauthenticated root RCE via crond.