The remote host is vulnerable to a buffer overflow.
It is possible to crash the remote MDaemon server by supplying an oversized argument to the CREATE imap command. An attacker may use this flaw to prevent other users from fetching their email. It will also crash other MDaemon services (SMTP, POP), thus preventing this server from receiving any email as well, or even to execute arbitrary code on this host with the privileges of the mdaemon IMAP daemon.
Upgrade to MDaemon 6.7.10 or later.