How to Check if SMTP Port 587 is Not Blocked

How to Check if SMTP Port 587 is Not Blocked

Before you get to use SMTP port 587 to send out emails, you need to check its connection first. Here, we will show you how to check if the SMTP port 587 is not blocked. By the end of this article, you’ll be able to know whether or not you can integrate the port with your email service.

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What is SMTP Port 587?

Port 587 is the default mail submission port that supports all types of SMTP data transmission. Supported by the majority of servers, this port is a popular choice for handling mail submissions. Combined with TLS encryption, SMTP port 587 ensures your emails are secure and delivered safely.

How to Check if SMTP Port 587 is Not Blocked?

Despite port 587’s popularity, not all hosting services support it. Therefore, it’s essential to check the port’s availability before integrating it with your email service.

Here’s a step-by-step guide on how to check if SMTP port 587 is not blocked:

1. Accessing System Console

Here’s how to access the system console in either Windows, Linux, and macOS:


  1. Press Windows+R keys together.
  2. On the Run window, enter cmd and click OK (Ctrl+Shift+Enter to run it as administrator).
  3. Windows command prompt window should appear.
    Using Windows command prompt.


  1. Press Ctrl+Alt+T keys together.
  2. Linux terminal window should appear by now.


  1. Press the F4 key.
  2. Enter terminal in the Launchpad’s search field and press Enter.
  3. macOS terminal window should appear by now.

2. Using Telnet Command to Check SMTP Port 587 Connection

Telnet is a network protocol that enables remote control over computers. It also lets you test whether a specific port is accessible or not. We’ll be using the Windows command prompt for this example.

Here’s how to use telnet command to check SMTP port 587 connection:

  1. Write down the following line in your console. Be sure to change the domain name accordingly.
    telnet yourdomain.tld 587

    Using the telnet command to test SMTP port 587's connection.

  2. If the SMTP port 587 is not blocked, the 220 response will appear.

    Note: This message may vary from system to system.

    220 message indicating that SMTP port 587 is not blocked.
  3. If Unable to connect or Connection refused message appears, that means the port is blocked. In this case, we recommend you to disable the firewall or contact your ISP.


As hosting services don’t support SMTP port 587, it’s essential to check the port’s connection before integrating it with an email service. We hope this tutorial helps you verify whether or not the port is blocked on your network.

The Author


Edgaras G. / @edgaras

Edgaras is a veteran server administrator at Hostinger. He makes sure that every server runs at full throttle and has all the latest technological advancements. When he's not working, Edgaras enjoys skiing and exploring the world.

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mike Reply

August 29 2019

This is great Advice. Love it. keep up the good work.


Daniel Carnovale Reply

September 02 2019

Perfect! Nice quick way to test, thank you :)


Steven Reply

June 29 2020

This is a solution I have found elsewhere. Need to setup a new firewall rule.


Phil Reply

September 25 2020

This is the answer I get on the console. 'telnet' is not recognized as an internal or external command, operable program or batch file.


    Tomislav T.

    Replied on November 18 2020

    Hey there Phil. I can't check the issue from here, but perhaps you can message our support team to help you out? :)


Marc DD Reply

November 19 2020

Hi Phil, Telnet is no longer standard installed on Windows 10. Go in settings to "Apps & Features", Look in "Related Settings" for "Programs and Features", select "Turn Windows Features on or off" (you will need administrative privileges) and find in the list "Telnet Client". Put a check mark next to it and click "Ok". Windows will install the command. If you do not have administrative privileges contact your IT division. There are several other commands like FTP which are also not installed by default.

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