"554 Relay rejected for policy reasons" error

I'm trying to add a second Internet domain to my server for Web and email addressing. My ISP has pointed the DNS Zone file and MX record to our server IP. I've created a Virtual Host record on the Domino server and the domain web site (e.g., "http://newdomain.com") comes up okay. And I created a Person record in the NAB with mail address in the new domain (e.g., "john@newdomain.com"). But I get "554 Relay rejected for policy reasons" error message when trying to email to this above address.

Download this free guide

Download: IT Certifications 101

Inside this exclusive essential guide, our independent experts break down which IT certifications are worth your time and effort, and how to get started obtaining them to further your career— including specific certifications that any cloud or desktop pro should seriously consider.

Start Download

• Corporate E-mail Address:

  You forgot to provide an Email Address.

  This email address doesn’t appear to be valid.

  This email address is already registered. Please login.

  You have exceeded the maximum character limit.

  Please provide a Corporate E-mail Address.

By submitting my Email address I confirm that I have read and accepted the Terms of Use and Declaration of Consent.

By submitting your personal information, you agree that TechTarget and its partners may contact you regarding relevant content, products and special offers.

You also agree that your personal information may be transferred and processed in the United States, and that you have read and agree to the Terms of Use and the Privacy Policy.

What am I doing wrong?

You need to put the domain in your Global Domain Document as an alternate domain.