How to configure the K1000 appliance to support using email address logins for the enduser portal rather than an Active Directory common name.
While samaccountname= KBOX_USER is commonly the basis for LDAP search filters, it is not the only one allowed. Please see https://support.quest.com/kb/112277 for a list of other filters which can be used.
NOTE: How SSO authenticates is entirely dependent on Active Directory configuration. If email addresses are used to log into the K1000 appliance, then email addresses would have to be used throughout the domain environment in order for SSO to work on the K1000 appliance.