Original title: Outlook.com trying to contact wrong server to send email

Users on outlook.com (business users) cannot send to an email domain not on outlook.com.  The NDR is

There was a SMTP communication problem with the recipient's email server.

<nadc2.dgna.net>

The problem is the email domain they are sending to has nothing to do with nadc2.dgna.net.  An mxlookup on the destination email domain resolves to asp.reflexion.net

All other companies can send to this domain, just not Oulook.com users.  Outlook.com users get a NDR saying the above.

Why is Outlook.com trying to send to nadc2.dgna.net when the destination domain's mx record is asp.reflexion.net?