I reinstalled my system again. Followed Falko's instruction close to every single letter.
I now have a kind of working system with ISP Config as well.
My problem now is as follows:
I can send emails to the domains I've created in ISP Config example.com and example1.com
Meaning I can send email from email@example.com
But when I try to send emails to firstname.lastname@example.org
I get the following message in my /var/log/maillog
Aug 09 18:45:39 myhostname postfix/smtp: 74FBF30501:
to=<email@example.com> relay=none, delay=10,
status=deferred (Name service error for name=gmail.com
type=MX: Host not found, try again)
But when I send an email from gmail.com to the domain I created in Postfix using ISP Config, I can receive the email successfully.
It only seems to be a problem while sending the email out of my LAN network.
I've an ADSL router and it is configured to allow connections on the following ports:
I did not install Firewall that comes in FC4 and I disabled SELINUX just as told to in Falko's instructions.
Is there anything else I need to do with regards to postconf configuration which would help my postfix send emails from AUthorised users like the ones created of ISP Config to send emails to others like @hotmail.com, yahoo.com, gmail.com etc etc.,
Thanks for your time and help. Much appreciated.