For Example, if we want to sent email to zulfan@kebo.vlsm.org,  frist, we must know about MX for this domain :
# host -t mx kebo.vlsm.org
kebo.vlsm.org mail is handled by 10 kebo.vlsm.org.

# telnet kebo.vlsm.org 25
Trying 202.154.187.9…
Connected to surobuaya.vlsm.org.
Escape character is ‘^]’.
220 howie.eepis-its.edu ESMTP Postfix (Debian/GNU)

And then named of  the sender :
MAIL FROM: <zulfan_hakim@yahoo.com>
250 2.1.0 Ok

If you don’t want to mention  the sender’s name  (Return-Path blank),we can write :
MAIL FROM:<>

Named of the receiver :
RCPT TO: <zulfan@kebo.vlsm.org>
250 2.1.5 Ok

This RCPT line can be repeated by the others  ( if  there’s any receiver ), for example we want to send this email for three people  in the same domain :
RCPT TO: <user1@kebo.vlsm.org>
RCPT TO: <user2@kebo.vlsm.org>
…
Note: If the domain were different, we have to call that different MX domain.

Then sent that body of email , and ended with a line contain with dot(.)  :
DATA
354 End data with <CR><LF>.<CR><LF>
Subject: Test
this is only a test, please pay attentioned
.
250 2.0.0 Ok: queued as 6762913F6F7

For Exit:
QUIT
221 2.0.0 Bye
Connection closed by foreign host.