Yes — email.posthog.com has IPv6.

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

B
IPv6 readiness
Works over IPv6, with one gap: www doesn't fully work over IPv6.
Website over IPv6
email.posthog.com has 4 IPv6 addresses and answers on every one we tested (4 more not tested).
✓ 2600:9000:201d:2400:14:1aa6:5540:93a1 answers · 443✓ 2600:9000:201d:6400:14:1aa6:5540:93a1 answers · 443✓ 2600:9000:201d:c600:14:1aa6:5540:93a1 answers · 443✓ 2600:9000:201d:e600:14:1aa6:5540:93a1 answers · 443– 2600:9000:201d:b400:14:1aa6:5540:93a1 not tested– 2600:9000:201d:c000:14:1aa6:5540:93a1 not tested– 2600:9000:201d:9c00:14:1aa6:5540:93a1 not tested– 2600:9000:201d:9800:14:1aa6:5540:93a1 not tested
yes
www over IPv6
www.email.posthog.com has no AAAA record.		no
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.
rory.ns.cloudflare.com ✓julissa.ns.cloudflare.com ✓
yes
HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate: HTTP 404.
https://email.posthog.com/ via 2600:9000:201d:2400:14:1aa6:5540:93a1 → 404
works
 Load email.posthog.com over IPv6 from up to six other places — a second opinion.

What's keeping email.posthog.com from an A

  1. Add IPv6 for www.email.posthog.com
    www.email.posthog.com has no AAAA record. Get www's IPv6 address from whoever hosts www and add it as an AAAA record. If the same server already serves both names (and its certificate covers www), you can reuse email.posthog.com's AAAA record(s) for www. How to add an AAAA record

Check again

email.posthog.com  Has IPv6

Alias ofd6o9p0tbz3txx.cloudfront.net
A (IPv4)13.226.209.108
13.226.209.77
13.226.209.82
13.226.209.74
AAAA (IPv6)2600:9000:201d:2400:14:1aa6:5540:93a1
2600:9000:201d:6400:14:1aa6:5540:93a1
2600:9000:201d:c600:14:1aa6:5540:93a1
2600:9000:201d:e600:14:1aa6:5540:93a1
2600:9000:201d:b400:14:1aa6:5540:93a1
2600:9000:201d:c000:14:1aa6:5540:93a1
2600:9000:201d:9c00:14:1aa6:5540:93a1
2600:9000:201d:9800:14:1aa6:5540:93a1

www.email.posthog.com  No address

A (IPv4)none
AAAA (IPv6)none

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

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

Checked 2026-11-01 23:05:36 UTC. Full DNS report: dns.pizza/domain/email.posthog.com · JSON: /api/v1/email.posthog.com