The POP3 server (EPSTPOP3S.EXE) 4.22 in E-Post Mail Server 4.10 allows remote attackers to obtain sensitive information via multiple crafted APOP commands for a known POP3 account, which displays the password in a POP3 error message.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42035
http://www.vupen.com/english/advisories/2008/1389/references
http://www.securitytracker.com/id?1019930
http://www.securityfocus.com/bid/28951
http://www.e-postinc.jp/Mail_Server.html