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Troubleshooting Email Issues Using Telnet

Joe Knows Support

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Troubleshooting Email Issues Using Telnet


Hi, I'm joe with and you're watching Joe Knows Support. Let's see how I can help you today. "Order Up!" What do we got? Ah, how to troubleshoot email issues using Telnet. Not to be confused Skynet, which my colleague John Connor knows all about and will be explaining to you in the not too distant future. Alright, let's take a look.


So, the first thing that we want to is go to and we're going to find out what our MX record is. So, we're going to do an MX lookup. Come down here, and right here under hosting it will actually tell us where our MX record name is. From here, we can open up a command line prompt and actually Telnet right into this MX record. We want to end this MX record with space 25.

All right, the first thing we're going to do is we're going to greet the server, and the server is going to come back. Then we're actually going to put in a mail from an email address and then a mail to, which will actually be a recipient to. Now, we're going to do it wrong here so we can see what would happen if it's not done correctly. I am going to put in, send it. This actually came back with an NDR code: 5.7.1. Now it gives you a high-level explanation what's going on there but if you want to know more about it you can go ahead and research that.

So, what we'll do now is type an another email address and see if we can make that work. But, unfortunately since we've already tried an incorrect recipient we're going to have to quit this session. So, you are going to see this fail also. Yes, it failed, so we can't do that. So we are going to quit this session and start over. You just type quit and we are going to lose that connection.

Now, let's start over and actually do this in a way to where we can see what we should be wanting to see. So, we are going to log back in, greet the server, do a mail from, and a good email address and we're going to pick a good recipient. Once we do this, it will tell us the connection is good. Now, we type data, and we can put in something funny like Feed Me or Hello Stephen. Then we will put a dot after that, and that will cue up the send. That'll go out, and now they'll receive that. We didn't get any type of errors there so we know that it is actually working correctly. So there you go!


All right, now, on NDR codes, you can research those online and find out more about them. And that's another ticket served.

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