"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.