When SMTP messages are being blocked by a firewall, which of the following implementations can be performed on Cisco Unity Connection to rectify this issue?

A.
Ensure that messages can be sent in MIME format in Cisco Unity Connection.

B.
Change the SMTP port number to match those ports that are used for the audio.

C.
Configure an SMTP smart host, where all SMTP traffic can be sent

D.
There are no workarounds to this problem

Explanation:
wrong in AT ‘Ensure that messages can be sent in MIME format in Cisco Unity Connection’.

StudentGuide Volume 2 Page 4-32
Cisco Unity Connection can route SMTP messages for VPIM locations or for other digitally networked Cisco Unity Connection servers through the smart host. For example, use the smart SMTP host when a firewall prevents direct SMTP communication with the remote voice messaging system.