cannot receive emails from a different user in the same domain

cannot receive emails from a different user in the same domain

Dear All,

I have setup 5 email accounts with my personal domain. All is working fine (I can send and receive emails from all the 5 user accounts). The problem is that I can't receive email coming from a different user in the same domain.

e.g. if with frank@mydomain.com I send an email to bill@mydomain.com, I can't receive the email in Bill's account.

Any suggestions?

THANKS

Cesare