public company · US

Duolingo, Inc.

Primary official domain
duolingo.com
Reviewed official domains
1 (directory review; organization has not verified)
Directory source
BreachScout directory · Suggest a correction
Matching domains, 30 days
1
registrable domains containing the brand; source date or last feed observation
First source-reported, 30 days
0
domains first source-reported within 30 days
First observed, 30 days
4
domains first observed by DomainSpoof in feeds
Email policy (primary domain)
DMARC reject
SPF Could not fully evaluate (sender-specific macros) · Mail: Not checked · checked 2026-10-18 · published policy

What we watch for

Hostnames in phishing feeds and certificate logs are matched on these brand tokens; feed target labels are matched on the aliases. Generated spellings (typos, lure words, look-alike characters, other top-level domains) are derived from the official domains and tokens and checked against feeds, certificate logs and DNS.

Brand tokens
duolingo
Label aliases
duolingo
Official domains
duolingo.com (all)
Generated spellings
116 tracked · 55 observed somewhere · 61 not observed (all)

Official domains and email policies

Domains reviewed as belonging to Duolingo, Inc.. DMARC helps receivers check the From domain; lookalike domains remain possible. Published policies cannot confirm actual mail configuration or receiver behavior.

DomainRelationshipEvidenceDMARC policyPolicy sourceSPFReportingMailDKIMMTA-STSLast check
duolingo.com
primaryReviewed —
Portfolio directory (financedb_ticker_A)rejectDirectCould not fully evaluate (sender-specific macros)Aggregate reports requested (rua)Not checkedUnknown (no known selector)
Not checkedNot checked
2026-10-18 22:58 UTC
Records and check details

Published records

DMARC (_dmarc.duolingo.com)
v=DMARC1; p=reject; sp=reject; fo=1; rua=mailto:…@DMARC.postmarkapp.com,mailto:…@inbound.dmarcdigests.com,mailto:…@duolingo.com; ruf=mailto:…@duolingo.com; adkim=r; aspf=r
SPF (duolingo.com)
v=spf1 ip4:100.25.59.11 ip4:205.201.128.0/20 ip4:198.2.128.0/18 ip4:148.105.8.0/21 ip4:52.73.203.75 ip4:52.70.130.33 include:amazonses.com include:_spf.google.com include:_spf.salesforce.com include:mail.zendesk.com include:aspmx.pardot.com ~all
MX (duolingo.com)
Not checked
DKIM
Unknown (no known selector). DKIM use requires a known selector or message to assess; a published key alone cannot confirm signing, and no key at the probed common selectors proves nothing.
MTA-STS (_mta-sts.duolingo.com)
Not checked
TLS-RPT (_smtp._tls.duolingo.com)
Not checked

Interpretation

  • p=reject: receivers are asked to reject failing mail.
  • Relaxed DKIM alignment (default).
  • Relaxed SPF alignment (default).
  • Could not fully evaluate: the record uses sender-specific macros (for example %{i}) whose targets depend on each sending host, so a static check cannot evaluate them and this is not reported as a valid record.
  • ~all (softfail): unlisted hosts are marked suspicious; this is not +all and does not by itself bypass DMARC.
  • At least 7 DNS-querying terms (include, a, mx, ptr, exists, redirect), counted recursively; the limit is 10.

Observations

  • SPF (sender-specific): _spf.salesforce.com: exists:%{i}._spf.mta.salesforce.com uses a sender-dependent macro

DMARC discovery (RFC 9989 tree walk)

  1. _dmarc.duolingo.com: ok, 1 DMARC record

Recent checks

  • 2026-10-18 22:58 UTC: DMARC reject; SPF could not fully evaluate

Assessment posture-v2. DNS lookup failures leave the policy unknown.

“Not checked”: no check yet (mail, DKIM and MTA-STS facts were added later, so older checks show “Not checked” for them). “Lookup failed”: DNS result unknown. DKIM is probed at a fixed list of common selectors only. Report mailbox names are redacted.

Reports on official domains appear under “Official assets with reports” on the Reported matches tab.