Unresolved domains

Unresolved domains

Hi I have different accounts with you guys, and I have the same issue, I'm trying to send emails to accounts @monocromatico.com.mx and @studioesq.com and they get bounced with the error message:

This message was created automatically by mail delivery software. 
A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. 

horacio@monocromatico.com.mx  Domain Not Resolved 
 

I did a quick check up to see if they have their MX entries added at  http://who.is/dns/thedomainname and they appeared ok, the problem has been intermittent since last week.

On the other hand I have no problems sending emails to the mentioned accounts using msn.com, gmail.com, or yahoo.com email accounts.

I would appreciate if you can shed some light on this, thanks!