> Aug 21 10:22:59 stretch postfix/smtpd[8394]: warning: hostname > mail.radio-z.net does not resolve to address 136.243.54.124 > Aug 21 10:22:59 stretch postfix/smtpd[8394]: connect from > unknown[136.243.54.124] > Aug 21 10:22:59 stretch postfix/smtpd[8394]: 18D3F6A40A2B: > client=unknown[136.243.54.124] > > The reverse DNS for that host is set (IPv4 and IPv6) and seems to work.
In case you use the standard resolvers provided by your data center, you could install a local resolver like unbound. /etc/resolv.conf: nameserver 127.0.0.1 Best regards Gerald
