21co.com

Valid Email Server
Domain Lookup › 21co.com

Domain Overview

DNS: ✓ 2mo ago Checker: ✓ 2mo ago
21co.com
Yes
✓ Yes
Outlook
No
No
⚠ Yes
No
No
Did you mean: [email protected]

Checked via [email protected] · 2026-03-22 22:39:07 UTC · ↺ Refresh

MX Hostnames

  • 21co-com.mail.protection.outlook.com

MX Priorities

  • 21co-com.mail.protection.outlook.com: 9

A / AAAA Records

  • 13.55.22.83 ↩ ec2-13-55-22-83.ap-southeast-2.compute.amazonaws.com

Mail Server IPs

  • 52.101.11.3 ↩ mail-sn1pr0501cu00103.inbound.protection.outlook.com
  • 52.101.8.46 ↩ mail-dm6pr05cu00406.inbound.protection.outlook.com
  • 52.101.11.13 ↩ mail-sn1pr0501cu00205.inbound.protection.outlook.com
  • 52.101.40.4 ↩ mail-cy5pr03cu00204.inbound.protection.outlook.com
  • 2a01:111:f403:c946:: ↩ mail-ch5pr02cu00200.inbound.protection.outlook.com
  • 2a01:111:f403:f908:: ↩ mail-bn1pr21cu00100.inbound.protection.outlook.com
  • 2a01:111:f403:c91d::a ↩ mail-co1pr21cu00202.inbound.protection.outlook.com
  • 2a01:111:f403:c931::1 ↩ mail-sa9pr03cu00201.inbound.protection.outlook.com

SOA Record

Raw SOA ns1-09.azure-dns.com internet-domains.21co.com 149 3600 600 604800 60
Primary NS (mname)
ns1-09.azure-dns.com
Admin Email (rname)
internet-domains@21co.com
Serial
149
Refresh
3600s
Retry
600s
Expire
604800s
Minimum TTL
60s

Nameservers (NS)

ns3-09.azure-dns.org
ns4-09.azure-dns.info
ns1-09.azure-dns.com
ns2-09.azure-dns.net

SPF Record

✓ Soft Fail (~all)
v=spf1 mx a:smtp-cbo.21co.com a:smtp-dco.21co.com ip4:104.209.35.28 ip4:104.251.20.150 ip4:104.251.17.0/24 ip4:104.251.31.0/24 ip4:52.8.140.255 ip4:35.169.47.31 ip4:18.217.82.134 ip4:54.164.132.26 include:spf.protection.outlook.com include:spf.us.exclaimer.net include:spf.cn005072.zixworks.com include:mail.verity.cloud ip4:104.251.16.4 ~all
📊 DNS lookups: 7/10
~ Soft fail (~all) — moderate enforcement

DMARC Record

✗ Missing

No DMARC record — emails cannot be rejected on auth failure.

DKIM Selectors

✓ 2 found
selector1._domainkey
selector2._domainkey
✓ Public key: 216 chars (valid)
✓ DKIM properly configured for selector: selector1

Checked: google, selector1/2, default, mail, dkim, k1, s1/2, zoho, sendgrid, mxvault, amazonses

All TXT Records

9 records
  • atlassian-domain-verification=iaej1pfJ5pCkpAu1Un5U7IQYi3hXIoBpxiqqejVJaeUalPwhUKaTm1atYVVWERGz
  • atlassian-domain-verification=vGoJUmPa7sg/AgjuPoQFFdbeztSpr40Lzg6XgtdSgmmUPArtMh29JAmJRcKDQrda
  • SPFv=spf1 mx a:smtp-cbo.21co.com a:smtp-dco.21co.com ip4:104.209.35.28 ip4:104.251.20.150 ip4:104.251.17.0/24 ip4:104.251.31.0/24 ip4:52.8.140.255 ip4:35.169.47.31 ip4:18.217.82.134 ip4:54.164.132.26 include:spf.protection.outlook.com include:spf.us.exclaimer.net include:spf.cn005072.zixworks.com include:mail.verity.cloud ip4:104.251.16.4 ~all
  • _f1um30x0r93wn99hozm6vlf2fapdkef
  • _q8gxx3i68v817wd1b0f384u41wtyts4
  • apple-domain-verification=4MDT5rRW2r0ZFURU
  • MS=A43A96D4CBDAC66410CBEDF7306D73765FCB7991
  • knowbe4-site-verification=d51c70fdb5913259da377622a6636942
  • fSLAHNqB2Dc5ZqTanvNIKzlwsOiA2OiPPodYWlrX4WgNIH0Mtn7abT2K36rPWq0a/bGsevyVgrOUOja70qoPlg==
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