Ok so I have solved the issue myself..
Just wanted to share how I did it.
Seems if you follow the tutorial, "Perfect ISPCONFIG Ubuntu Setp" everything gets installed including smtp server.
Right next setup your DNS servers with and A Name record to point to your Ubuntu Server with ISPConfig.
smtp.yourdomain.com ... .to point to your server IP.
*** Always remember that DNS changes might take some time to resolve accross the WWW, so be patient"
Once you can ping smtp.yourdomain.com .... and it shows that its pointing to your server... you know it game on !
Also make sure that the IP is for the correct server ie. your ubuntu server.
Now just setup your email client (Outlook, Macmail etc ) to use and Autenticated smtp server for sending mails, and your set.
Thanks Falco for some awesome tutorials...