Not receiving e-mails from a specific client?

[Emad]

Hi,

I am using Yahoo Small Business for more than two years and just recently I came across strange problems with the e-mail. I stopped receiving e-mails from only one client's domain while I kept on receiving all e-mails from different domains. My client has told me that all the e-mails he's sending are bouncing back with error called "NON-DATA" he even tried sending me e-mails from different users with the same domain but didn't reach me and got the same bouncing back error. The e-mails are not being received in the Spam folder as they just bounce back!!!

Also I'm having a problem with duplicate e-mails which is extremely annoying especially that I have Yahoo mail app in my mobile and it keeps on receiving e-mails.

Can anyone help me!!