#Flush of all rules
iptables -F
#permit SSH access
iptables  -A INPUT -p tcp --dport 22 -j ACCEPT
#Permit local traffic
iptables  -A INPUT -p tcp -s 127.0.0.1/8 -j ACCEPT
iptables  -A INPUT -p tcp -s <LOCAL_IP> -j ACCEPT
#Permit access from you workstation
iptables  -A INPUT -p tcp -s <YOUR_CLIENT_IP> -j ACCEPT
#Block all Zimbra ports for incoming traffic
iptables -A INPUT -i eth0 -p tcp -m multiport --dport 25,80,110,143,443,993,995 -j REJECT
#Block all Zimbra outgoing traffic
iptables -A OUTPUT -o eth0 -p tcp --dport 25 -j REJECT