Topic: ports to be blocked.

I installed and successfully running iredmail open source version with postfixadmin.
In Iptables file, you have oepned 80,443,25,465,110,995,143,993,587,465,22 port to all.
Now i would like to host this iredmail server exteranlly to some of my friends for testing.
For this , i need to install the mail server in DMZ zone of firewall.
What question what are changes needed in iptables file
a).if i allow only http access,SMTP access, POP3 access and IMAP access to external users.
b). https access only to internal network so that only internal users can operate postfixadmin,phpmyadmin etc.