HOW.IS
?

How is customer.io?

Looks fine risk 0/100

Registered 15 years ago, on no blocklists we checked, valid HTTPS, the site answered 200 in 110 ms.

Why

02050100
finecarefulhigh risk
  • ·Nothing in the checks added risk.

Rule-based: domain age, blocklists, TLS. A heuristic, not a guarantee.

How customer.io looks right now
The home page, rendered by how.is in a sandboxed browser. Nothing on it is clickable here.
Site
200
110 ms
HTTPS
82 d
left on a Let's Encrypt certificate
Age
15 years
registered 2011-10-26
Blocklists
0
listings across 5 lists

Everything we looked at

DNS records4 record types
A76.76.21.21
MX1 aspmx.l.google.com
10 aspmx2.googlemail.com
10 aspmx3.googlemail.com
5 alt1.aspmx.l.google.com
5 alt2.aspmx.l.google.com
NSns-1181.awsdns-19.org
ns-1893.awsdns-44.co.uk
ns-499.awsdns-62.com
ns-618.awsdns-13.net
TXT1password-site-verification=NKRDO4YCMBDD7KNUO4PN6RZCA4
MS=ms56053829
OSSRH-70026
airtable-verification=a839ac25097d07e90b6725421494b506
anthropic-domain-verification-h4s30h=RXWAAyC4VDThCnWjaprWPkUET
asv=8738dd37f3c5a1368cba93d24b4a1e17
cursor-domain-verification-m2k2b5=XfoK2FPHAUqoNHiCpHtqY2fXP
docusign=48e7526a-7539-4ad0-b672-7a94c3a20c29
facebook-domain-verification=62g2j16g5qkvf38ekdrtxiez0bsqei
google-site-verification=HbwteWh_QF6HnNCDLL_1X_GRwURBkYEdFAVM00rxf_k
google-site-verification=gsxlVNPtm1JCawWVNMCOVuWLK9lhzdr4Dofz-V-lovo
have-i-been-pwned-verification=a9d6f2edb8654dcfe04e310cdc9a000a
hubspot-developer-verification=NDkzOTIwZWMtMDVkNS00YTAzLThlMDQtZDJmYzVjNzc5Zjgw
jetbrains-domain-verification=rdxczp2suguw502vrx4cqksy
linear-domain-verification=wetdfvhymmbh
loom-site-verification=4dac5f34468e49a299444383229599d5
miro-verification=89a8ecb5df4f4febc758723fcfabd5af59041414
mixpanel-domain-verify=d5c389d5-df00-473a-8263-3932c19beecb
notion-domain-verification=DHmczCmyAqc8TGp6DPbfWBxLb9lSgvPv7wSOiiJfAJK
openai-domain-verification=dv-icOHzM0IplqgpTNoO3nJaRCX
ps-cd-verification=6d210b55-ec4b-4105-a1d7-7a73c78619fd
sinch-domain-verification=77675a95-7309-44bf-9483-5f9020edc778
slack-domain-verification=XRnWU545ZVlzHN85aeTWX7xzunEJk8Ouav9KjN7Q
v=spf1 include:helpscoutemail.com include:_spf.google.com include:servers.mcsv.net include:amazonses.com include:mail.zendesk.com ~all
zapier-domain-verification-challenge=3373ff99-18e1-4a49-8e81-67d830eb392b
Registration1API GmbH
registrar1API GmbH
registered2011-10-26
expires2027-10-26
last changed2026-10-26
ownerPeaberry Software Inc.
nameserversns-1181.awsdns-19.org
ns-1893.awsdns-44.co.uk
ns-499.awsdns-62.com
ns-618.awsdns-13.net
statusclient transfer prohibited
registered 2011-10-26expires 2027-10-26
HTTPS certificate82 days left
validyes
issuerLet's Encrypt
coverscustomer.io
protocolTLSv1.3
issued 2026-10-25expires 2027-01-23
DNSSECinsecure

Domain is not signed with DNSSEC

. → io → customer.io
Email authenticationexcellent
SPFpass v=spf1 include:helpscoutemail.com include:_spf.google.com include:servers.mcsv.net include:amazonses.com include:mail.zendesk.com ~all
DMARCpass policy quarantine
DKIMfound: google, k1, s1, s2, smtp

Whether mail claiming to be from this domain can be checked as genuine.

Security scoregrade B · 165/205
Basic Security
20/40missing: DNSSEC Enabled
Record Security
30/45missing: CAA Records, DKIM Presence
Advanced Security
20/25missing: IPv6 Support
Domain Reputation
50/50
Threat Detection
45/45missing: Domain Age Check
Blocklists0 listings · 5 lookups
SURBL MultidomainURIBL MultidomainSpamCop76.76.21.21Barracuda76.76.21.21UCEPROTECT Level 176.76.21.21

Green: clean. Red: listed. Grey: the list did not answer.

Ask it yourself

Agents get this as data. Bought through the API, the checks behind this page cost $0.070: profile $0.025 + trust $0.020 + screenshot $0.020 + site status $0.005.

curl "https://how.is/v1/domain/trust?domain=customer.io" \ -H "Authorization: Bearer $HOWIS_KEY" # or pay per call in USDC (x402), no key: the 402 tells your agent the price curl -i "https://how.is/v1/domain/profile?domain=customer.io"

MCP: add https://how.is/mcp to Claude, Codex or Cursor (one-line install) and ask for domain_trust on customer.io. Reference: /llms.txt.

IPv6. IPv6 readiness grade for customer.io Does customer.io work over IPv6? See the live check on aaaa.bot — website, mail and nameservers, graded A–F.

Watch customer.io. DNS read at the source every 5 minutes; certificate, blocklists and expiry every 6 hours. You get an email only when something changes.

Watch — $1 / 30 days