The remote IMAP server is prone to multiple vulnerabilities.
The remote host is running AXIGEN Mail Server, a messaging system for Linux and BSD. The IMAP server component of AXIGEN Mail Server is affected by two denial of service issues involving PLAIN and CRAM-MD5 authentication methods. An unauthenticated remote attacker can leverage these issues to crash the IMAP service and possibly even execute arbitrary code remotely.
Upgrade or patch according to vendor recommendations.