Originally Posted by nehrumoorthi
I am willing to configure a mail and dns server now i am very blind and dont know from where to start please anyone can guide me..
I am using RHEL 5 ..
When you asked before, you were "guided" to Google. There are two mail servers available to you: postfix and sendmail. Both run very well on Linux, and both have MANY how-to guides that even a quick Google search will turn up. Same for DNS.
Since you're using RHEL, and paying for support from them, call RedHat. They can guide you through a setup process, and (since you're also paying for access to their knowledgebase and package repository), have docs on how to set it all up and download it.