Your users can't receive emails sent to their account in these custom domains: {0} The NS or MX records of the domain (DNS) ...

Your users can't receive emails sent to their account in these custom domains: {0}

The NS or MX records of the domain (DNS) settings aren't configured for email delivery to your Office 365 service.

How to fix it
Go to the Domains page in the Office 365 Admin center, and we'll help you fix the settings.