Q. How can I check that my Exchange (or any other) email server isn't usable as an SMTP relay for everyone on the Internet?

A. A big concern when you introduce services to the Internet is that they'll be misused. The last thing you want is for someone to use your email server as an SMTP relay to send out huge amounts of spam, causing your IP to be blocked, stopping legitimate email.

I found a good site that lets you type your domain name and then run diagnostics such as seeing if SMTP relay can be performed anonymously, the SMTP Test option. Once you run the test, you're looking for a green button and "Not an open relay." If it says something else then you need to check your email configuration and rectify the problem ASAP.

You want to see something like this:

and not this:

I'm sure there are other services on the web, I just liked this one because it was easy to use. You can perform the same type of check with the Exchange Best Practices Analyzer and tools such as Sam Spade.

Related Reading:

Check out hundreds more useful Q&As like this in John Savill's FAQ for Windows. Also, watch instructional videos made by John at ITTV.net.
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