accountsettings_add.html in Merak Mail Server 7.4.5 with Icewarp Web Mail 5.2.7 and possibly other versions allow remote attackers to create text files with arbitrary content via the accountid parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17317
https://euvd.enisa.europa.eu/vulnerability/EUVD-2004-1667
http://www.securityfocus.com/bid/11371