This indicates an attack attempt to exploit a Cross-Site Scripting vulnerability in SecurEnvoy SecurMail.
The vulnerability is due to insufficient sanitizing of user supplied inputs when the vulnerable software handles a maliciously crafted HTTP request. A remote attacker may be able to exploit this to execute arbitrary script code within the context of the application, via a crafted HTTP request.
SecurEnvoy SecurMail 9.1.501
System Compromise: Remote attackers can execute arbitrary script code within the context of the target user's browser.
Apply the latest patch from the vendor.