Your network is a mixed environment of Windows, Linux, and UNIX, computers. The routers are primarily Cisco and the network uses a T-1 to connect to the Internet. You are experimenting with setting up a mail server in a production environment for internal use only. You do not want this mail server to receive any requests from anywhere but the internal network. Therefore you have decided to block incoming SMTP traffic at the Firewall. Which port will you block at the Firewall?

A.
23

B.
25

C.
53

D.
80

E.
110