crnjaz wrote:could you tell me how? what command?
If you are going to do port forwarding (not recommended for Zimbra BTW...) instead of 1:1 NAT in your router, you need to set the router up to port forward all of the Zimbra ports. https://wiki.zimbra.com/wiki/Ports
Alternatively, configure a private DNS server for Zimbra to use so that Zimbra will always resolve its FQDN to itself instead of to the interface on the router. See https://wiki.zimbra.com/wiki/Split_Domain to do that.
Hope that helps,