Useful SMTP Command

The following article will outline some basic SMTP command which you can use in order to :

- Test SMTP server working or not
- Test Open relay of a SMTP Server

Here are the steps & command you can use:

• Open command prompt if you are using windows or using Linux terminal and type the following command:

$ Telnet <SMTP SERVER> 25

where <SMTP SERVER> is the host IP Address or Hostname of your SMTP server, for example your SMTP host name is SMTP.4bing.com, then you might want to type: 

$ Telnet  smtp.4bing.com 25 

• You'll receive greeting from the server as below from the server, which means a session has already been established

220 smtp.4bing.com Microsoft ESMTP MAIL Service, Version: 7.0.6001.1800 0 ready at  Tue, 30 Jun 2015 15:12:50 +0700

• Continue with the following command  

1. Type HELO <your mail server domain>, and then press ENTER.
2.  Type MAIL FROM:<sender@domain.com>, and then press ENTER.  
3. Type RCPT TO:<recipient@remotedomain.com>,and then press ENTER. 
4. Type Data , then continue with Subject: <Your Email Subject> and then press ENTER
5. After step 4 above you can now type anything as mailbody
6. when finish with your mailbody type "."  and then press Enter 
7. Type Quit to end the session and email should be sent out if everything works perfectly

•  see below example