The remote host is vulnerable to a buffer overflow.
The remote host is running WebSTAR Mail, a mail server for Mac OS X that offers its services via a web interface. WebStar runs with the Tomcat plugin enabled by default. This version of WebStar is vulnerable to an attack against the Tomcat plugin. Specifically, a long, user-supplied URI will result in a buffer overflow. Successful exploitation would lead to the execution of arbitrary code on the remote server.
Upgrade to a version greater than 5.4.1.