E-mail systems related to the following protocols:

(1)SMTP: Simple Mail Transfer Protocol, which is used to send mail and works on port 25.

(2)POP3: post office protocol V3.0, used to receive mail, working port 1 10.

SNMP simple network management protocol, the default transport layer protocol is UDP port 25.

HTTP hypertext transfer protocol, the default transport layer protocol is TCP port 80.