No — mail.colorado.edu is IPv4 only.

Has an IPv4 address but no IPv6 (AAAA) record. IPv6-only visitors can't reach it directly.

D
IPv6 readiness
The website has no IPv6.
Website over IPv6
mail.colorado.edu has no AAAA record.		no
Mail servers (MX) have IPv6
None of the mail servers has an AAAA record.
inbound-reply.s7.exacttarget.com ✗
no
Nameservers have IPv6
6 of 6 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
a11-66.akam.net ✓a1-153.akam.net ✓a2-67.akam.net ✓a20-65.akam.net ✓a3-66.akam.net ✓a22-67.akam.net ✓
yes

What's keeping mail.colorado.edu from an A

  1. Give mail.colorado.edu an IPv6 address
    Ask your hosting provider for the site's IPv6 address (or the hostname to point at), then publish it as an AAAA record. If your host doesn't offer IPv6, a proxy that does can sit in front. How to add an AAAA record
  2. Mail servers without IPv6
    inbound-reply.s7.exacttarget.com has no AAAA record, so mail from IPv6-only servers can't reach it directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.

Check again

mail.colorado.edu  IPv4 only

A (IPv4)136.147.129.27
AAAA (IPv6)none

What this means

Visitors on IPv6-only networks (many mobile carriers) can still reach it, but only through a translator their carrier runs (NAT64). The site itself has no IPv6 address — and you can't make one up from the IPv4. Why some hosts don't offer it

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

 Permanent link: aaaa.bot/r/pTMkh3xSlG · How we measure

Checked 2026-11-03 06:01:55 UTC. Full DNS report: dns.pizza/domain/mail.colorado.edu · Age, certificate and blocklists: how.is/mail.colorado.edu · JSON: /api/v1/mail.colorado.edu