Before I was using virtualmin everything works fine, when I switched to cwp I am facing this issue. I can send emails but can't receive . please help me how to fix it
that should be some simple issue but you would need to check logs about an issue (postfix/dovecot).
http://wiki.centos-webpanel.com/service-log-paths
You can also try to rebuild mail server from cwp and then check incoming emails again.
I am using free DNS from cwp, and changed name servers to default mails are working now.