The Microsoft Exchange IMAP4 service must be disabled.
The IMAP4 protocol is not approved for use within the DoD. It uses a clear text based user name and password and does not support the DoD standard for PKI for email access. User name and password could easily be captured from the network allowing malicious user to access other system features. Uninstalling or disabling the service will prevent the use of the IMAP4 protocol.