I'm trying to host the e-mails and the site of our company into our private server. I've already followed the Gentoo Virtual Mailhosting System with Postfix Guide and my mail server is working (actually it sends mails for the local users and for external users it goes to spam) and know how to set an Apache 2 server. What I don't know (and I mean really don't) is how to make them public.

I did some research and found that I should ask my ISP to change the reverse DNS to my company domain in order to prevent my mails to be marked as spam, they are doing.

I already know I have to configure a DNS Server, it seems like my register provider already has one but I don't know how I can configure CNET, A, MX, TXT and all those tags (Is it tags the name?) and If I must do some other configuration on my server.

My Server:

Linux mail 3.2.21-gentoo #1 SMP

My /etc/hosts:

127.0.0.1 mail.example.com.br example example.com.br

::1 mail.example.com.br mail example.com.br

My /etc/conf.d/hostname:

hostname ="mail"

What am I missing? If there's a guide about how to configure I would really be grate. Thanks in advance for the help.

Cheers