Exim - host lookup did not complete

Ошибка вида:

2016-03-22 13:33:17 H=localhost (195.154.231.28) [::1] sender verify defer for <[email protected]>: host lookup did not complete
2016-03-22 13:33:17 H=localhost (195.154.231.28) [::1] F=<[email protected]> A=auth_plain:[email protected] temporarily  rejected RCPT <[email protected]>: Could not complete sender verify

Решение - прописать корректные ДНС сервера в резолвер:

# cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4

Перезапускаем exim (CentOS 7)

# systemctl restart exim