======================================= Debian disable ipv6 ======================================= Unless you have configured a firewall that addresses ipv6 networking you should disable ipv6. ======================================= /etc/sysctl.conf --------------------------------------- net.ipv6.conf.all.disable_ipv6 = 1 --------------------------------------- sysctl -p ======================================= /etc/exim4/update-exim4.conf.conf --------------------------------------- dc_eximconfig_configtype='satellite' dc_other_hostnames='host.domain.com' dc_local_interfaces='127.0.0.1' dc_readhost='host.domain.com' dc_relay_domains='' dc_minimaldns='false' dc_relay_nets='' dc_smarthost='smarthost.mailhost.com' CFILEMODE='644' dc_use_split_config='false' dc_hide_mailname='true' dc_mailname_in_oh='true' dc_localdelivery='mail_spool' disable_ipv6='true' --------------------------------------- update-exim4.conf systemctl restart exim4 ======================================= done =======================================