The remote host is vulnerable to a number of Denial of Service (DoS) attacks.
The remote host is running the Atrium Software MERCUR mail server, a POP3, SMTP and IMAP server. This version of MERCUR is vulnerable to a number of flaws in the way that it handles user-supplied commands. Some of the commands do not require prior authentication. An attacker exploiting these flaws would be able to cause the MERCUR server to fail. Successful exploitation would result in the loss of availability.
Upgrade to version 2005 SP4 or higher.