dig fails to find microsoftsupport.com

[David]

An update.

The topic was
Re: Postfix sending to A not MX

It appears the problem is with DNS.  Looking up using 'dig mx'
   microsoftsupport.com
fails, whereas looking up other domains (theregister.com, cnn.com, 
outlook.com) work just fine.

One correspondant saw the same using different configurations.
Do others see this?  Is there something about microsoftsupport.com 
that causes dns not to work?

I do notice that "microsoftsupport.com" has a DNS entry but does not 
have an A-entry, and has an MX record with an explicit priority of 
zero zero.  Do either of those make a difference?

David