frmAddfolder.aspx in SmarterTools SmarterMail 1.6.1511 and 1.6.1529 allows remote authenticated users to create a folder that SmarterMail cannot delete or rename via a folder name with a null byte ("%00"). NOTE: it is not clear whether this issue poses a vulnerability.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15392
http://www.zone-h.org/advisories/read/id=4098
http://members.lycos.co.uk/r34ct/main/smarter_mail%203.1/smarter_mail.txt