[winston] IPv6 is badly mis/not-configured; email issues
proton.parabola.nu has no public IPv6 address, but it does have an IPv6 address via lvpn. So it thinks it has IPv6. So, when delivering an email, if it sees an AAAA record, it thinks that's a fine address to deliver to, but if it tries to connect, it will get "network unreachable". On the other hand, it might just happen to choose the A record, and everything is happy.
So, SMTP servers that are accessible via both IPv4 and IPv6 intermittently have emails dropped.
Updated by lukeshu about 1 year ago
- % Done changed from 100 to 90
- Status changed from fixed to confirmed
Wait, I screwed up IPv6 rDNS, so some IPv6 mail servers were rejecting
our email (including my mav.lukeshu.com).
I've fixed the rDNS, and have disabled IPv6 in postfix until the 24
hour DNS ttl expires.