I have create domain1 and domain2, 3 and 4 within Mail Domains configuration. MX for all these domains are pointing to the server same ISP 3.1 server under CentOS. I have then added domain2, 3 and 4 to Domain Alias and display is correct. When I send a mail from my mail account @domain2 to @domain1 I correctly receive my mail but from other servers mails are not coming to alias domains, principal domain works fine. Any idea ?
You are the boss and you were right, I was having a trouble within my DNS entries for MX record. Many thanks for your answer.