Send Smtp From Command Line

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Send Smtp From Command Line – In this article, I will show you how to verify the existence of an email using the command line. I think you can do it manually without sending the email, just to verify its existence.

1. Find or find the mail servers of the target domain, i.e. the domain part of the email address you want to verify.

Send Smtp From Command Line

Send Smtp From Command Line

In other words, it is finding the MX records of the domain in the DNS zone file. If the destination domain serves such an email address, it must be served from an exchange mail server and MX records should be configured to define how to handle incoming/outgoing email.

Test Smtp Connection Using A Manual Telnet Session

Displays one or more mail servers. We will access one of these mail servers to perform the verification.

Your results may differ from mine, but we only have access to one of these Google mail servers to do this work.

I’ve written a step-by-step tutorial on how to check MX using the command line. Check it out if you want to know more about it.

And for this we will use the telnet utility. You may want to install it, if it is not available on your computer, proceed with the command.

How Email Actually Gets Sent: A Look At Smtp

If that works, you should be inside the telnet shell of that server, from there you can issue commands to request actions.

At this point you should be inside a telnet prompt accessing the MX server. If not, try step 2 again.

Command Used to initiate communication between telnet and mail servers. It actually wants to communicate with SMTP to send mail. It will respond with a list of commands available for SMTP communication.

Send Smtp From Command Line

, it is about entering the email address of the recipient and we should enter the email that we want to verify on these mail servers. In the above example I entered

Sending Tls Mail To Exchange From The Command Line

Check the description, it’s a very descriptive response from Gmail. However, it may not be so clear for other mail servers. But you’ll know if the email is there or not by looking at the response code, 550.

As I said, verifying the existence of an email is very easy, anyone can do it using the command line. Follow the detailed steps in this tutorial to do it.

If that seems too complicated, you can verify the existence of the email simply by sending a test email to the destination email address. If it’s not there, you’ll receive an email notification. Before we look at sending TLS mail to Exchange, let’s talk about using the command line to send mail without TLS.

The command you use to send a simple email to Exchange is the telnet client. It is no longer installed by default, but you can install it by adding the Windows feature for the telnet client. Once it is installed, you can use the following command

Simple Java Mail

The first thing you need to do after connecting to EHLO or HELO is to tell Exchange who you are. Although Exchange doesn’t really care what name you give it, the default name you enter is your fully qualified domain name.

What you do next depends on the options that Exchange has given you. There should be one option that starts with 250-AUTH, now if it says LOGIN then you can use basic authentication, but if it says NTLM Exchange expects NTLM authentication. You can also try to send mail without logging in, although Exchange will usually reject this if your original IP address is not trusted for anonymous mail delivery.

Assuming Exchange has LOGIN on line 250-AUTH, perform a basic authentication login. Please note that we do not use TLS, so these credentials may be intercepted on the network. Exchange expects the username and password to be Base64 encoded to ensure that no special characters interfere with the command syntax. For Base64 encoding you can go to

Send Smtp From Command Line

If everything went as planned, Exchange should now say 235 2.7.0 Authentication Successful. Okay, so now we’re ready to send the email!

Send File As Attachment Or Email Body From Command Line

First, you must be from an address, you must have rights to send from that address, or Exchange must be configured to trust you as any sender.

Then you need one or more recipients, the people who will receive this email. Exchange needs to know about these recipients or be configured so that you can contact anyone.

Now we are ready to write the email itself, it can be just the body of the message, as well as any other headers included

If you want to include a header and message body, add the header first one line at a time and then a blank line before starting the message body. At the end of the email, put . online and Exchange will process the message. If all is well, you will receive a response code of 250 2.6.0 Mail queue for delivery

Run A Command And Send The Output To An Email On Linux

Okay, now you might be thinking, well, there are tons of tutorials on how to telnet mail, but if I type STARTTLS after EHLO, I don’t get any more… That’s true, but I wanted to give a quick summary of how to use the basic SMTP commands. You can use all of the above with TLS mail as well, the trick is to first use openssl instead of telnet. You can download Openssl from

Now you can add switches like -ssl3 -tls1 -tls1_1 -tls1_2 to force openssl to use a specific encryption protocol, so it’s a good idea to check if your server is protected from vulnerabilities like POODLE and BEAST etc.

Twan is a senior consultant with over 30 years of experience. Has a wide range of skills including messaging, Active Directory, SQL, networking and firewalls. Twan loves writing scripts and diving deep into code debugging to understand and solve the most complex problems.

Send Smtp From Command Line

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How To Send Email To Smtp Server

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Testing Smtp Relay Server Connection Issues Without Using Telnet

Nothing should be returned, if you get a response like below you are missing a mail handler package…

Now after running the command again there should be no output but the email may not arrive due to…. problems.

If your server has an invalid domain name, smtp connections will be rejected – configure a server with a valid domain name.

Send Smtp From Command Line

If your smtp connection is outgoing, make sure outgoing port 25 is enabled, some providers block this by default.

How To Install And Configure Postfix As A Send Only Smtp Server On Ubuntu 20.04

If you already have Postfix installed on your server, and most rotating servers already do, you may need to reconfigure Postfix with the correct domain name and parameters you submitted.

Inet_interfaces ensures that it only receives email from the local computer, sets the server to send email and receive email only from the loopback address.

This directive is not in the file by default, add it to the end of the file if you want to use it.

If you want or need you can use relay because your IP address is blacklisted, there are many solutions with some providers offering a free tier account, 2 popular ones are SendGrid and MailGun.

Smtp Port 587 Fails To Send Messages With Ssl Checked (seeing 502

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