The SMTP service (MESMTPC.exe) in MailEnable 3.x and 4.25 does not properly perform a length check, which allows remote attackers to cause a denial of service (crash) via a long (1) email address in the MAIL FROM command, or (2) domain name in the RCPT TO command, which triggers an "unhandled invalid parameter error."
http://www.securitytracker.com/id?1024427
http://www.securityfocus.com/bid/43182
http://www.securityfocus.com/archive/1/513648/100/0/threaded
http://www.mailenable.com/hotfix/
http://www.mailenable.com/Standard-ReleaseNotes.txt
http://www.mailenable.com/Professional-ReleaseNotes.txt
http://www.mailenable.com/Enterprise-ReleaseNotes.txt