How to use Telnet to send email over Port 25 using SMTP

A popular request coming in is from students who wish to become more proficient in general computing topics. For this, we at AskStudent will be writing a series of articles such as this article where we will talk about the Telnet command and how you can use it to access your mail server using Port 25 and sending an email to someone using nothing but your command prompt.

How to send Email using Telnet command over port 25 using the SMTP protocol

Telnet: TELNET (TELetype NETwork) is a network protocol used on the Internet or local area network (LAN) connections. It was developed in 1969 and standardized as IETF STD 8, one of the first Internet standards. Read more about Telnet in the Wikepedia article here 

SMTP: Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. Read more about SMTP in this Wikipedia article here

Step # 1: First, open a command prompt. To open a command prompt window, click Start, Run and then type in cmd and press Enter. You can also press the +R to open the Run prompt and then type in cmd in the open text box.

Step # 2: You need to know a remote mail server. If you are still in school or working, there is the excellent opportunity to use your University mail server or your company’s mail server for this.

type in telnet RemoteMailServer 25 at the command prompt. The Remote mail server here in this command is the mail server of your school or company. It is usually mailhost..edu or compmail..com or something on those lines. When you press enter, you are shown a quick prompt that you are connecting to the remote mail server.

Step # 3: Introduce yourself to the mail server. Play around a bit.

type in helo mailhost at the command prompt. The mail server responds back with something like this

250 RemoteMailHost. Hello , pleased to meet you.

Step # 4: You can now enter your email address.

type in mail from: your email id @ blah.com

The mail server responds back with a 250 … sender ok

Step # 5: You can now enter your receipient’s email address

type in rcpt to: recipient email id @ blah.com

The mail server responds back with a “Recipient OK” message

Step # 6: Now, you are ready to type in the body of the email message.

type in data and press enter.

Now, type your message and then finally press Enter. To end your message type in a single period “.” . Your message is now in the queue

Step # 7: To complete and finish the process, type in quit and press enter. The mail server responds with a “Bye” after which you see a “Connection to host lost” message displayed.

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