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Using Telnet for a dialog with SMTP server




I read the book “Computer Networking – A Top Down Approach”, and there after the head about the SMTP protocol Task:

“IT IS Highly Recommended That You Use Telnet to Carry Out a Direct Dialogue with An SMTP Server. To do this, Issue

  • Telnet ServerName 25

Where Servername Is The Name Of A Local Mail Server. WHEN YOU DO THIS, YOU ARE SIMPLY ESTABLISHING A
TCP Connection Between Your Local Host And The Mail Server. After Typing This Line, You Should
Immediately Receive The 220 Reply From The Server. THEN ISSUE THE SMTP COMMANDS HELO, MAIL
From, rcpt to, data, crlf.crlf, and quit at the approprte times. “

That’s what I tried:

  1. I: telnet smtp.mail.ru 25
  2. Server: 220 SMTP48.I.Mail.Ru Esmtp Ready
  3. I: Helo Aaaaaaa
  4. Server: 250 smtp48.i.mail.ru
  5. I: Mail From: … @ Inbox.ru (my mailbox)
  6. server: 250 2.0.0 ok
  7. I: RCPT to: … @ Inbox.ru (my friend’s mailbox)
  8. Server: 550 SMTP IS AVAILABLE ONLY WITH SSL OR TLS Connection Enabled.

What am I doing wrong? And in general, as I understood from reading this chapter, SMTP is a protocol that is used to transmit e-mail messages from one mail server to another – is it possible to perform this task from my laptop on which there is no server software? Or should I somehow open the command line exactly on some kind of mail server, via Telnet to create a TCP connection with another mail server and send to the mail server to which connected, message? If it is still possible to somehow do, then what should be the sequence of steps so that everything is completely completed successfully?

Answer 1

You do everything right in the framework of the study task.

Unfortunately, since the book was written, much has changed.

Problem in spammers.

Because of spam activity, almost all public servers – which means that the server on which your friend’s mailbox is located – have a “white sheet of IP addresses, with the cats they take the mail.” Well, or “Black list of spam servers from which they do not accept mail.”

In addition, now many postal servers simply do not accept SMTP letters without SSL encryption. And to dress an exercise using SSL – this is most likely to go beyond the framework of the curriculum.

So you need to find an SMTP server, which is not filtered by IP 2 connections) does not use SSL. I’m afraid in the wildlife could not stay. You can install it yourself, just to perform the task. Well, or set a couple of such servers and exchange letters between them. Google by “SMTP Server Docker”

I have come back with unprotected SMTP servers from the provider [Best-Hosting.ru] 1 – this is not advertising. As unich now – I do not know: -)

And more – when entering text, you need to complete the entry of the point on a separate line and the translation of the line after this point

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