Help Regarding OS X Server

Hello

We are having a Mac Mini in which OS X Server (v 10.9.5) is installed.

We want to use this OS X Server as a mail server.

We are having following:

1. OS X Server

2. Static IP

3. Domain Name - purchased from GoDaddy

Now, I want to configure mail accounts and want to send and receive all email from this server.

Secondly GoDaddy has not provided any mail ids to me.

My question is whether I have to purchase Email addresses from GoDaddy or I can create my Email Id in the Server.

Secondly please help me about creating MX records as well.

Any help would be appreciated.

Thanks in advance.

Tattwam