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Telnet SMTP commands

What is telnet ?

Telnet is a network terminal protocol means you can user telnet protocol for accessing a remote terminal. Remote server require a TELNET server has to be installer.
TELNET also can be use for accessing remote terminals for protocols, like if a SMTP or HTTP server is installed you can access their terminal using telnet on their specific ports.
Here we will access remote terminal of SMTP server and will use SMTP commands for checking the mail functionality.

Sending a test mail from SMTP command

Connect your SMTP server using telnet

telnet <host> <port>

telnet 25
You should receive a reply like in Microsoft SMTP server
220 ServerName Microsoft ESMTP MAIL Service, Version: 7.5.7600.16385 ready at  Mon, 16 Jun 2014 22:25:46 +0530

Now you have to send helo to your SMTP server and let him know from where you are sending this email


you will get reply like this
250 Staging-PC Hello []

Define your sender name
You should get ans like this
250 2.1.0 ….Sender OK

Now give the recipients address:
You will get ans like this
250 2.1.5

Start writing your content.


354 Start mail input; end with <CRLF>.<CRLF>
Subject: Test email from zoladius
<your content here>

250 2.6.0 <SERVER-Nameq8eNFHOZT00000005@Server-Name> Queued mail for delivery

Write your content and complete your message with period sign “.”
Close the connection
221 2.0.0 Staging-PC Service closing transmission channel
Connection to host lost.

Take a quick look at command table

Telnet SMTP Commands
HELO <HOSTNAME>  Initiate SMTP Communication with Server
EHLO <HOSTNAME>  Same as HELO but for the ESMTP server
MAIL FROM: <sender email id>  Sender email id
RCPT To: <recipent email id>  Recipient  email id
DATA  Initiate writing your content
Subject: <email subject>  Email subject name
Cc: <CC user email >  CC email id
Reply-To: <Reply email address>  Replay to email id
VRFY username
 Verify username from recipent SMTP server
QUIT  Quit SMTP conversation with server