IPSwitch IMail 6.0.5 allows remote attackers to cause a denial of service using the SMTP AUTH command by sending a base64-encoded user password whose length is between 80 and 136 bytes.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5674
http://www.securityfocus.com/bid/2083
http://www.ipswitch.com/Support/IMail/news.html
http://archives.neohapsis.com/archives/bugtraq/2000-12/0071.html