use Telnet to connect to mail server.

simple commands:

HELO <ip-address-of-mail-server> 

The mail server should respond.

telnet: > telnet smtp
telnet: Trying
telnet: Connected to
telnet: Escape character is '^]'.
server: 220 ESMTP server ready Tue, 20 Jan 2004 22:33:36 +0200
client: HELO
server: 250
client: MAIL from: <[email protected]>
server: 250 Sender <[email protected]> Ok
client: RCPT to: <[email protected]>
server: 250 Recipient <[email protected]> Ok
client: DATA
server: 354 Ok Send data ending with <CRLF>.<CRLF>
client: From: [email protected]
client: To: [email protected]
client: Subject: Test message
client: This is a test message.
client: .
server: 250 Message received: [email protected]
client: QUIT
server: 221 ESMTP server closing connection


telnet 25


MAIL from: <[email protected]>

RCPT to: <[email protected]>

From: <[email protected]>
To: <[email protected]>
Subject: Test message

This is a test message.
  • tech-notes/smtp.txt
  • Last modified: 2018/05/17 20:05
  • by gerardorourke