smtp.eonet.ne.jp publishes IPv6 but doesn't answer on it.

Has both IPv4 (A) and IPv6 (AAAA) addresses.

This is a saved measurement from 2026-11-15 18:08 UTC. Check smtp.eonet.ne.jp live now

IPv6 readiness

Publishes IPv6 but doesn't answer on it — worse than having none.

Website over IPv6 smtp.eonet.ne.jp has an AAAA record, but nothing answered on ports 443 or 80. IPv6 visitors wait for a timeout before falling back to IPv4. ✗ 2001:240:bb81:94:202:238:198:30 no answer	broken
Mail servers (MX) have IPv6 No MX records, so mail goes to the domain's own address (implicit MX). It has an AAAA record.	yes
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. ns1.eonet.ne.jp ✓ns7.eonet.ne.jp ✓	yes

What's keeping smtp.eonet.ne.jp from an A

Fix or remove the AAAA record for smtp.eonet.ne.jp
Something published an IPv6 address but nothing answers on it, so IPv6 visitors wait for a timeout first. Either make the server listen on IPv6 (and allow ports 443/80 through its firewall), or delete the AAAA record until it does.

Check again

smtp.eonet.ne.jp Has IPv6

Alias of	kopt-eonet-smtp.xspmail.jp
A (IPv4)	202.238.198.30
AAAA (IPv6)	2001:240:bb81:94:202:238:198:30

Browsers on dual-stack networks will usually pick IPv6 here (the "Happy Eyeballs" algorithm races both and prefers v6).

Copy the evidence — a citation-ready record of this measurement

IPv6 measurement: smtp.eonet.ne.jp
Measured 2026-11-15 18:08:41 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    202.238.198.30
AAAA (IPv6): 2001:240:bb81:94:202:238:198:30

Readiness grade F: Publishes IPv6 but doesn't answer on it — worse than having none.
- Website over IPv6: smtp.eonet.ne.jp has an AAAA record, but nothing answered on ports 443 or 80. IPv6 visitors wait for a timeout before falling back to IPv4.
    2001:240:bb81:94:202:238:198:30: no answer
- Mail servers (MX) have IPv6: No MX records, so mail goes to the domain's own address (implicit MX). It has an AAAA record.
- Nameservers have IPv6: 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.

Reachability = a TCP connection opened on port 443 (or 80).
No TLS or HTTP request was made.
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/AovaE1Z2tn

Permanent link: aaaa.bot/r/AovaE1Z2tn · How we measure

Checked 2026-11-15 18:08:41 UTC. Full DNS report: dns.pizza/domain/smtp.eonet.ne.jp · Age, certificate and blocklists: how.is/smtp.eonet.ne.jp · JSON: /api/v1/smtp.eonet.ne.jp