reboot in hetzner rescue and reconfigure the network configuration script .

it will be port conflict . You may check the following two documentations
https://wiki.zimbra.com/wiki/Zimbra_Proxy_Guide
https://wiki.zimbra.com/wiki/Zimbra_Proxy_Manual:Installing_,_Configuring,_Disabling_the_Zimbra_Proxy

First thing is you should check the maillog at the time for sending . You can see everything in that file.

What is your server type. I can see the load is little high in your server.

Hi Swan,

No manual. it is basic linux networking , I am working with linux before it had GUI lol

Please see the complete code below, edit it properly #cat /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 BOOTPROTO=none ONBOOT=yes HWADDR=90:1B:0E:8B:10:65 IPADDR=136.243.150.152 NETMASK=255.255.255.192 GATEWAY=136.243.150.129 #SCOPE="peer 136.243.150.129" IPV6INIT=yes IPV6ADDR=2a01...

Sometimes , you may need to add the route-eth0 file too to add the route 136.243.150.129 dev eth0 default via 136.243.150.129 eth0 For ubuntu add the following in interface file up route add -net 136.243.150.128 netmask 255.255.255.192 gw 136.243.150.129 eth0

Hi,

It was hetzner

Yes, To solve this issue . Please do it as follows,
Edit the file /etc/sysconfig/network-scripts/ifcfg-eth0 and change the line of peer with GATEWAY. Then restart the network. That will solve the issue.

Yes , that was the reason . I figured it out. The server provider use peer instead of gateway.