I've just setup a mail server on a CentOS dedicated server. I can successfully send email and receive email, using TLS and everything, so that part is perfect.
The problem, however, is that I can't send emails to people from the same server using an email from the same server.
So, firstname.lastname@example.org can't send emails to email@example.com, but firstname.lastname@example.org can send emails to both email@example.com and firstname.lastname@example.org.
I can't send emails from email@example.com to firstname.lastname@example.org.
A snippet from my maillog:
Dec 22 07:58:34 king postfix/smtpd: NOQUEUE: reject: RCPT from mail-qy0-f172.google.com[188.8.131.52]: 550 5.1.1 <email@example.com>: Recipient address rejected: User unknown in virtual alias table; from=<firstname.lastname@example.org> to=<email@example.com> proto=ESMTP helo=<mail-qy0-f172.google.com>
Not too sure what information to give, so let me if you need more info. As I said, I can email firstname.lastname@example.org properly using my email@example.com.
Note: All email addresses are fictional.
EDIT: I should specify that I use Virtualmin. I have the virtual_alias_maps set in my main.cf to
virtual_alias_maps = hash:/etc/postfix/virtual. In the virtual file, I got plenty of entries generated by Virtualmin such as: