I have created around 6 email ids with my domain www.lamzing.com. It was working and all of a sudden its not working on some specific scenarios

My email id *** Email address is removed for privacy *** can sent out to yahoo, gmail and other email accounts. I can also receive emails from other account. However the following scenario doesn't work

  *** Email address is removed for privacy *** -> *** Email address is removed for privacy *** doesn't work

  *** Email address is removed for privacy *** -> *** Email address is removed for privacy *** doesn't work

  *** Email address is removed for privacy *** -> *** Email address is removed for privacy *** and vice versa doesn't work.

  These are the only conditions it doesn't work and I am at lost to understand why its not working. They are all part of my same domain and it used to work before.

  I just realized that I cant even send myself a test mail. I have put @lamzing.com as safe senders also.

  Please help me here.