What must be configured to allow the Cisco ESA to encrypt an email using the Cisco Registered Envelope Service?
A. provisioned email encryption profile
B. message encryption from a content filter that select “Message Encryption” over TLS
C. message encryption from the mail flow policies with “CRES” selected
D. content filter to forward the email to the Cisco Registered Envelope server
Correct Answer is A
https://www.cisco.com/c/dam/en/us/products/collateral/security/esa-cres-encryption.pdf