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Home > Success Center > Network Performance Monitor (NPM) > NPM - Knowledgebase Articles > Test SMTP server connectivity via telnet

Test SMTP server connectivity via telnet



If Orion alerts are functioning properly and the logs show that a message was sent to the SMTP server, but you didn't receive the expected email, you may need to troubleshoot connectivity between Orion and your SMTP server.



All NPM versions




If a user is not getting email and you want to test the SMTP server, you can use telnet to send a test email. This will verify connectivity to the SMTP server from the Orion server.


Important Note: This test must be performed on the Orion server experiencing the issue. It is not a valid test to perform from your workstation or PC.

Blue text indicates a command you will type in. 
Red italics indicates a key press


1. First, check if telnet is installed:

a. Start > Run > CMD > telnet <smtp-server> <port> <enter>

                  Example:  telnet 25 <enter>


If telnet is not installed, you will get something like this:



2. To install Telnet, please refer to Microsoft website. 


a. Start > Run > CMD <enter>

b.pkgmgr /iu:"TelnetClient" <enter>




If telnet IS installed, you will get something like this after entering the above command (telnet 25):



3. Type the following to send a test email:

  • ehlo me and press <enter>
  • mail from: <sender-email> <enter>
  • rcpt to: <recipient-email> <enter>
  • data <enter>
    • test_smtp_server_7.png
    • subject: Test 123 <enter>
    • <enter>
    • Hi there, this is a test <enter>
    • Finally, to finish the email, type a period (.) and <enter>
      • test_smtp_server_9.png
      • You should get a 250 OK - that means it was successful 
      • If you do not get a 250 OK, and get something else, refer to this guide:
        • This indicates the issue is likely on the SMTP server (likely not running an open relay or the user doesn't have a mailbox)
  • The recipient should then receive an email:



  • If you don't receive the email, contact your SMTP server administrator. 
  • If you do receive the email, you have eliminated connectivity to the SMTP server as a problem. 


Here's the full conversation for reference:







Keywords:  orion npm email alert action smtp server e-mail address fails sent received send 


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