IPv6 socket creation failed: Address family not supported by protocol

Question

OS: GNU/Linux Debian 9.2 64-bit

I disabled IPv6 on one of my servers.

And now I'm getting this in mail:

exim paniclog
...

IPv6 socket creation failed: Address family not supported by protocol

How do I get rid of it?

Solution

First of, man needs to disable IPv6 in exim4.

In the following file:

/etc/exim4/update-exim4.conf.conf

Make sure this line is there, if not, add it, or change it:

disable_ipv6='true'

But I tried only this solution and the mail is still coming, so digging further...

In the same file, make sure this line is set to true:

dc_minimaldns='true'

Now edit this file:

/etc/hosts

Let's suppose, this line defines your server name:

127.0.1.1   server-name

Change it as follows:

127.0.1.1   server-name.localhost server-name

Now, verify, that this command:

hostname --fqdn

Returns:

server-name.localhost

If so, you can update your Exim4 configuration:

update-exim4.conf

And restart the Exim4 service:

systemctl restart exim4.service