If you're trying to visit http://mail.yourdomain.com and it's not working. Please check the following:
1) You have login to your control panel -> hosting manager ->Website domain manger and mapped your domain to your account.
2) You have login to your control panel ->Email Manager and activated your email service.
3) You are using our DNS server ns1.site4now.net , ns2.site4now.net and ns3.site4now.net
If you are using your own DNS server. Please make sure you setup a Cname record and MX record. You can copy cname and mx record settings in your control panel ->DNS Manager . Once you copy these settings to your own DNS server, wait few hours and it should work.