Cannot receive mail on new domain

Cannot receive mail on new domain

I cannot receive emails on my new domain.

I verified my domain and enabled email on my account.  I added a user, changed the MX records at my provider, then I verified the settings through a web tool.

I can send messages successfully, but I cannot receive emails.  Instead of being sent, I get:
... tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 No Such User Here (state 13).