Linux Mail Server Setup and Howto Guide

Hi, i have a CentOS 6 server with postfix on it.

I can send message between users: like user@localhost and in exterior like user@gmail.com, but I can not receive mail from exterior.

I want to receive mails on root@ipaddress. I also have configured a no-ip.info DNS.

It is possible to receive email on root@domain.no-ip.info? If not I also have a bind DNS zone which looks like this:

$TTL 'value'
@    IN    SOA    (localhost.)    Zatarra@domain.info. (
            'value'; Serial
            'value'; Refresh
            'value'; Retry
            'value'; Expire
            'value'; Negative Cache TTL
            )
@    IN    NS    ns.domain.info.
@    IN    A    ipaddress
ns    IN    A    ipaddress
www    IN    A    ipaddress
ftp    IN    A    ipaddress
mail    IN    MX 0   ipaddress

Any idea how can I recieve mail on root@mail.domain.com, or at least root@domain.com

Let's say that the nameserver(dnsserver) for the domain is set with my ip address

Tnx in advance