How to Test your SMTP Server

By | May 21, 2014

If you are writing an SMTP agent, you might find it instructive to learn to speak SMTP yourself, both to aid debugging and to get a feel for what is happening “under the hood” when Exchange receives a message from the internet. This is a lot easier than it might sound. Open the Run dialog box (press Window + R) and enter “telnet localhost smtp” (or substitute the name of your Gateway server in place of localhost). This will open a window where you can talk with the server. The server will begin the conversation by sending a banner, such as: 220 ready at Thu, 23 Feb 2006 17:46:23 -0800 You may continue the conversation by entering the following commands, one line at a time. Note that there is a blank line in the middle – it’s important. Just press enter to send the blank line: ehlo console mail from: rcpt to: data To: From: Subject: Test Message This a test message. . quit Source:

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