Which Cisco Secure Email Threat Defense visibility and remediation mode is only available when using...

According to the Cisco Secure Email Threat Defense User Guide, the No Authentication option is only available if you are using a Cisco Secure Email Gateway (SEG) as your message source. This option allows visibility only, no remediation1.

The other options are not valid because:

A. Basic Authentication is not a visibility and remediation mode for Cisco Secure Email Threat Defense. It is a method of authenticating users with a username and password2.

C. Microsoft 365 Authentication is a visibility and remediation mode that allows you to use Microsoft 365 credentials to access Cisco Secure Email Threat Defense. It has two sub-options: Read/Write and Read. This mode is available for both Microsoft 365 and Gateway message sources1.

D. Cisco Security Cloud Sign On is not a visibility and remediation mode for Cisco Secure Email Threat Defense. It is a service that manages user authentication for Cisco security products, including Cisco Secure Email Threat Defense3.