m.karthikeyan Tips

SMTP Commands to Send Email Message

Sending an email message to a mail account using Telnet and SMTP commands. We are going to learn how to send an email message through SMTP commands. From one destination, without any client software.

I’ve tested it and sent an email message to my Gmail account from my test Virtual private server (VPS). Since broadband, IP is blacklisted and not permitted for sending email messages. Follow the below-recommended steps and continue until the end of the post.

Finding out mail server

I recommend using the NSLOOKUP command for Linux and Windows Operating system.

#nslookup -q=mx gmail.com
Non-authoritative answer:
gmail.com       mail exchanger = 30 alt3.gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 40 alt4.gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 5 gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 10 alt1.gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 20 alt2.gmail-smtp-in.l.google.com.

Select the low preference mail exchange server, and here I took gmail-smtp-in.l.google.com.

Sending email message through SMTP commands

[root@server ~]# telnet gmail-smtp-in.l.google.com 25
Trying 74.125.91.27...
Connected to gmail-smtp-in.l.google.com.
Escape character is '^]'.
220 mx.google.com ESMTP y15si15797390qci.149
helo
250 mx.google.com at your service
mail from:test@tothetech.com
250 2.1.0 OK y15si15797390qci.149
rcpt to:karthikeyannet@gmail.com
250 2.1.5 OK y15si15797390qci.149
data
354  Go ahead y15si15797390qci.149
to:karthikeyan .net@gmail.com
from:test@tothetech.com
Subject: Email messaging

Test message from my VPS server

Regards,
Karthik
.
250 2.0.0 OK 1291139912 y15si15797390qci.149
quit
Connection closed by foreign host.

We connected to the Google SMTP server on the port 25. With Telnet command, after a few seconds, the Google SMTP server welcomes us. Usually, SMTP communication starts with a HELO command. Next, you need to provide mail from:urname@urname.com. And the recipient address through rcpt to:yourname@gmail.com.

After providing mail from and rcpt to, you need to start Data. Where you need to provide To, From and Subject details and end the data by keeping (.) dot at the last of the conversation. After completing the data part, your email message queued up to the recipient address.

To exit this session type quit and exit the SMTP session, after that you can check your Gmail account.

email-messaging

 

Note: You can send email messages similar to any other email providers like Yahoo, Outlook with the same technique.