Debian / Ubuntu prefer to use IPv6 DNS Records. This leads to problems if the server supports only IPv4. The problem can easily solved. We only need to change the config for getaddrinfo(). Open /etc/gai.conf and change #precedence ::ffff:0:0/96 100 to precedence ::ffff:0:0/96 100 For me it was line 54.
To send outgoing mail with postfix for certain domains only over IPv6 or IPv4, only a few changes are required. The domains are registered in accordance /etc/postfix/transport examplev4.de smtp-ipv4-only: examplev6.de smtp-ipv6-only: /etc/postfix/master.cf: smtp-ipv4-only unix – – n – – smtp -o inet_protocols=ipv4 smtp-ipv6-only unix – – n – – smtp -o inet_protocols=ipv6 /etc/postfix/main.cf: transport_maps = hash:/etc/postfix/transport: Execute postmap hash:/etc/postfix/transport and […]