source: http://www.securityfocus.com/bid/1421/info

If an E-mail containing an excessively long To: field in the header (~1.5 MB) is processed by First Class Intranet Services (FCIS), a Denial of Service can occur. 

https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/20052.tar.gz