Buffer overflow in Citadel SMTP server 7.10 and earlier allows remote attackers to execute arbitrary code via a long RCPT TO command, which is not properly handled by the makeuserkey function. NOTE: some of these details were obtained from third party information.
https://www.exploit-db.com/exploits/4949
https://exchange.xforce.ibmcloud.com/vulnerabilities/39807
http://www.vupen.com/english/advisories/2008/0252
http://www.securitytracker.com/id?1019255
http://www.securityfocus.com/bid/27376