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Using Auth Login to Troubleshoot Exchange

Using Auth Login to Troubleshoot Exchange

This article explains the Microsoft syntax that SMTP needs to log into Exchange server 2010. Here are SMTP commands that you can try using telnet to test email.

I am embarrassed at how long it took me to master the SMTP verb Auth Login.  Rather than pretending that Auth Login is easy, I am going to go slowly and give you even more instructions than usual.  My mission is to explain how to send email from the command line. 

We will open a telnet shell and connect to the Exchange 2010 server.  Once we receive the 250 OK reply code, we will issue the SMTP commands to encode the password.

Before you go any further, ask yourself: Do I really need to authenticate?  Could I just try sending email using the plain commands, mail from: and rcpt to:? 

Another benefit of trying this simpler technique is that you will gain experience of the telnet and SMTP commands before you grapple with Auth Login and encoding.

0) Prerequisite - Get Your Base64 Encoder

It is essential that you obtain a base64 encoder.  Before you go any further you must be able to encode username and password.  For me, even this first step wasn't easy. Foolishly, I searched in Google for a 64-Bit encrypter instead of a base64 encoder.  So here are two important lessons, pay attention to detail, and this is where you can get a good base64 encoder: Opinionated.

Guy ThomasGuy ThomasGuy Thomas is a computer consultant and writer with attitude and a great sense of humor.