Hello, I have been running my own e-mail server for many years now, and have been native IPv6 for... maybe 5 or 6 years?
I never have any problems, except for delivering to Comcast users. I get bounces like this: A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: [email protected] SMTP error from remote mail server after initial connection: host mx2.comcast.net [2001:558:fe21:2a::6]: 554 resimta-ch2-08v.sys.comcast.net comcast ESMTP server not available [email protected] SMTP error from remote mail server after initial connection: host mx2.comcast.net [2001:558:fe21:2a::6]: 554 resimta-ch2-08v.sys.comcast.net comcast ESMTP server not available Googling a bit I see this: http://postmaster.comcast.net/smtp-error-codes.php Comcast requires all sending mail server IP addresses have a valid PTR record set up. This error results when the lookup failed. NXDOMAIN response. One of the authoritative servers for the relevant section of the in-addr.arpa DNS tree is saying that there is no PTR record for the given IP address. But I do have working reverse DNS: $ ip addr | grep inet6 inet6 ::1/128 scope host inet6 2a02:2770::21a:4aff:fea3:eeaa/64 scope global dynamic inet6 fe80::21a:4aff:fea3:eeaa/64 scope link $ host 2a02:2770::21a:4aff:fea3:eeaa a.a.e.e.3.a.e.f.f.f.a.4.a.1.2.0.0.0.0.0.0.0.0.0.0.7.7.2.2.0.a.2.ip6.arpa domain name pointer c.time-travellers.nl.eu.org. $ host c.time-travellers.nl.eu.org c.time-travellers.nl.eu.org has address 46.19.37.141 c.time-travellers.nl.eu.org has IPv6 address 2a02:2770::21a:4aff:fea3:eeaa The forward and reverse IPv6 DNS even match! Are there any recommendations? I hate to do AAAA filtering of Comcast's SMTP servers, but if that's the only way to work around the brokenness, I guess I will so I can talk to my family about their vacation photos... (Note that Comcast has no issues sending me mail, so I get a lot of vacation photos.) Cheers, -- Shane
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