Microsoft Exchange Server 2003 - SMTP Raw Commands
Introduction to Exchange Server 2003 SMTP Raw Commands
This page explains the raw SMTP commands that you can execute to troubleshoot email on an Microsoft Exchange 2003 server. Instead of sending email from Outlook, we will create a telnet shell and then type these SMTP commands, ehlo, Mail from: rcpt to: and data.
Topics for Microsoft Exchange 2003 SMTP Commands
Let us begin troubleshooting with an easy command. Suppose we wish to test that the SMTP service is running on an Exchange 2003 server. What we need is a telnet shell, so let us launch a cmd box and then type: Telnet server 25. Naturally, follow through by pressing the Enter key for the carriage return.
This is what you should see in the cmd box:
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This is what should what you should see when you type ehlo. (Remember to follow up ehlo by pressing the Enter key.)
SMTP Learning Points for Raw Commands
Let us finish as we started, by paying attention to detail. Here are 3 vital SMTP commands to master when you troubleshoot,
Now that you have mastered the SMTP command basics, here are ideas for how and why you would use these raw SMTP commands. For instance, raw SMTP commands are useful to troubleshoot relaying. If you try to send an email to recipient address outside your organization, then the reply will tell you whether or not that email is relayed. For example, the response maybe: 550 5.7.1 Unable to relay. Whereas if you can relay, then you would get the response of, 250 2.1.5.
If you're trying to solve the cause of NDRs, try emailing users at different Exchange 2003 servers, the raw command would be similar to, rcpt to: diffuser@ somewherelse.net
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As I hinted at the beginning, I found this raw SMTP technique difficult and had my fair share of these error codes. Most of my troubleshooting problems began with 5yz indicating a fatal error with that SMTP command.
421 - <service not available, closing channel> (domain)
Note: it would be unlikely if you got all these errors in one bunch!
Knowledge of how to issue raw SMTP commands is handy to troubleshoot email problems in general, and Exchange 2003 server in particular. The key to success is to open a telnet shell then practice SMTP commands such as, ehlo, mail from: and rcpt to:.