Setting the above env var, does not produce the corresponding line in the postfix configuration, resulting in trying to reach kopano-dagent over ipv6, even if this is not at all available.

`
root@mail-569fc74d58-p5rg2:/# echo $POSTFIX_INET_PROTOCOLS
ipv4
root@mail-569fc74d58-p5rg2:/# cat /etc/postfix/main.cf | grep ipv4
root@mail-569fc74d58-p5rg2:/#

`
It should have created the inet_protocols = ipv4 line properly.