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.
If you see host aspmx.l.google.com[2607:f8b0:400d:c02::1b] said: 550-5.7.1 [2607:5300:101::79e] Our system has detected that this message does 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and 550-5.7.1 authentication. Please review 550-5.7.1 https://support.google.com/mail/?p=i…tication_error for more 550 5.7.1 information. h1si3408978qew.71 – gsmtp (in reply to end of DATA command) the destination dropped […]
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 […]
There are various possibilities to deactivate IPv6 on linux-systems. You can modify entries under /proc, experiment with the kernel modules or god knows what all. I prefer to add just one entry to the grub-option. So i can easily reactivate IPv6 with one step. ipv6.disable=1 After a reboot, the IPv6 […]