messages sent to zoho mail servers does not go through, and does not bounce back?!?

01. November 2013 · Write a comment · Categories: Hotmail, Outlook.com · Tags: , ,
we have a custom domain setup with zoho mail, and sending test emails all go through except all live, outlook, and hotmail addresses.
the emails DO NOT bounce back.  I am able to send mail from zoho to outlook, but not the other way around.  this is puzzling.  zoho tech support tried everything came up empty.  yesterday, everything worked correctly, today there is an issue.  please help asap!

thank you