You work as a security administrator at Certpaper .com. The Certpaper .com network must be
configured to support e-mail communication using SMTP (Simple Mail Transfer Protocol).
Which ports must you open on the firewall to support SMTP connections?

A.
Open UDP (User Datagram Protocol) port 25 to inbound connections.

B.
Open UDP (User Datagram Protocol) port 110 to inbound connections.

C.
Open TCP (Transmission Control Protocol) port 25 to inbound and outbound connections.

D.
Open TCP (Transmission Control Protocol) port 110 to inbound and outbound connections.

Explanation:

TCP port 25 is reserved for SMTP while port 110 is for POP3.