source: http://www.securityfocus.com/bid/2636/info

"The Bat!" is an MUA for Windows by Rit Research Labs.

"The Bat!" is vulnerable to a remote denial of service attack. Email messages in which carriage return (CR) characters are not followed by a linefeed (LF) can cause "The Bat!" to incorrectly interpret the message's structure. This can lead "The Bat!" to read text in the message body as a response from the POP3 server. The current (corrupt) message will not be deleted from the server, and the mail download process will stop.

As a result, the user will remain unable to receive new email messages from the affected POP3 account. 

https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/bin-sploits/20783.zip