how do you get to the zimbra webmail?
you can access webmail from your web browser through these address:
http://127.0.0.1(if you are in the mail server - that server contain zimbra)
yourdomain.com or http://your_server_IP_address(if you have a dns and you access from a desktop)
First ping your zimbra server ip, its pinging when open brouser and type this
http://zimbra server ip