Unable to receive email but can send

I have setup virtualmin on my centos vps, I am able to send the emails but unable to receive emails. Can anyone help?

Is Port 25 open?

Many mail problems can be diagnosed by using Telnet, which provides more direct feedback about why the mail wasn’t accepted – assuming the attempt made it as far as the mail server. If it doesn’t, then most of the time it’s a firewall issue.

This article assumes the user is using Windows, but Telnet is available for literally any OS.

Richard