On Thu, Sep 19, 2024 at 11:29:23AM -0700, Seth Mattinen via mailop wrote: > Looking for someone who handles mail in duke.edu for a sub-delegation. I am > having problems with mail delays on @dm.duke.edu due to DNS lookup failures > causing domain does not exist errors.
The are of course (soft-fail) deferred, because the DNS lookup failures are not definitive, SERVFAIL is not NXDOMAIN. > 2024-09-18T10:22:33.457792-07:00 mail postfix/smtpd[4184837]: NOQUEUE: > reject: RCPT from unknown[2600:1806:511:210:1eaf::11]: 450 4.1.8 > <[email protected]>: Sender address rejected: Domain not > found; from=<[email protected]> to=<[email protected]> > proto=ESMTP helo=<mx1.dnsmadeeasy.com> > Looking at DNS shows me the following (and DNSViz): > > dm.duke.edu. 21600 IN NS nameserver1.mc.duke.edu. > dm.duke.edu. 21600 IN NS nameserver2.mc.duke.edu. > ;; Received 135 bytes from 152.3.105.232#53(dns-auth-02.oit.duke.edu) in 76 > ms > > nameserver1.mc.duke.edu has address 152.16.1.4 > nameserver1.mc.duke.edu has IPv6 address 2620:0:691:dc50::4 > > nameserver2.mc.duke.edu has address 152.16.1.12 > nameserver2.mc.duke.edu has IPv6 address 2620:0:691:dc57::12 But do you really only have IPv6 connectivity? Sadly, you really should have at least one IPv4-capable MX host whose iterative nameservers can reach the IPv4 Internet. Many mail systems are still only V4-capable, or their DNS is only available via IPv4 (no IPv6 NS IPs to even attempt to query). > Fails on IPv6: > > ; <<>> DiG 9.10.3-P4-Debian <<>> MX dm.duke.edu @2620:0:691:dc50::4 > ;; global options: +cmd > ;; connection timed out; no servers could be reached > > ; <<>> DiG 9.10.3-P4-Debian <<>> MX dm.duke.edu @2620:0:691:dc57::12 > ;; global options: +cmd > ;; connection timed out; no servers could be reached I see the same, and they really *should* fix this, but you'll continue to have problems with mail from other senders. Listing non-working IPv6 nameservers is substantially worse than not listing any IPv6 nameservers at all. -- Viktor. _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
