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DNS Tool
Engineer's DNS Intelligence Report
Generated 5 Mar 2026, 14:48 UTC
Duration 27.5s
Version v26.34.20
Integrity 378ed56af28e45906888e60a1d78f4aa269fca41077bc20328ef6e630bbf6a1d830a04f82dcf73d530881a4e0f6423d174c379455cf8b23fc4caed00ea40814e
Subject Domain
tuta.io

Engineer's DNS Intelligence Report

tuta.io Low Risk
5 Mar 2026, 14:48 UTC · 27.5s ·v26.34.20 · SHA-3-512: 378e✱✱✱✱ Verify ·Cross-Referenced
Executive Topology Replay
Recon Mode Snapshot Re-analyze New Domain
Engineer workspace · evidence preserved

Read the verdict first. Descend only as far as the incident requires.

This report keeps the complete technical record while separating decision, interpretation, evidence, and raw reproduction into a stable disclosure gradient.

L0PostureL1InterpretationL2EvidenceL3Raw & reproduce
Hurry path
MX & Routing Subdomains DNSSEC What changed
KEYBOARD !1@2#3$4%5^6 jump to that section · esc back to the verdict
Sorted by severity — worst first
Email Spoofing
Protected
Brand Impersonation
Not Setup
DNS Tampering
Protected
Certificate Control
Configured
Monitoring
Partial
DANE
Unconfirmed
TRACE L0 · Brand Impersonation — Not Setup L1 · 04 · Brand & Trust · BIMI L3 · Reproduce commands
Not Configured
BIMI
Recommended
Upgrade DMARC policy from quarantine to reject (p=reject) for maximum spoofing protection, Add DMARC aggregate reporting (rua) for visibility into email authentication
Configured
SPF (hard fail), DMARC (quarantine, 100%), DKIM, MTA-STS, TLS-RPT, DANE, DNSSEC, CAA
Priority Actions Achievable posture: Hardened
Medium Add DMARC Aggregate Reporting

Add a rua= tag to receive aggregate DMARC reports. Without reporting, you cannot monitor authentication failures.

RFC 7489 §7.1
Medium Upgrade DMARC to Reject

Your DMARC policy is set to quarantine. Upgrade to p=reject for maximum protection — reject instructs receivers to discard spoofed mail entirely rather than quarantining it.

RFC 7489 §6.3
Open Remediation Workspace — Copy-Paste Ready Records
Registrar (NS INFERENCE) INFERRED LIVE
Amazon Registrar
Inferred from NS records
Email Service Provider
Unknown
Moderately Protected
Web Hosting
Unknown
Where website is hosted
DNS Hosting OBSERVED
Amazon Route 53
Where DNS records are edited
Footprint 1 SaaS Service
01 Identity & policy · L1 Email Security Can this domain be impersonated by email? SPF DMARC DKIM MTA-STS TLS-RPT MX & Routing Protected
Email Security Methodology Can this domain be impersonated by email? Unlikely SPF and DMARC quarantine policy enforced

SPF Record RFC 7208 §4 Gold

Does this domain declare who may send email on its behalf? Yes
Success -all 1/10 lookups

SPF valid with strict enforcement (-all), 1/10 lookups

v=spf1 include:spf.tutanota.de -all
RFC 7489: -all may cause rejection before DMARC evaluation, preventing DKIM from being checked
RFC 7208 Conformant — This SPF record conforms to the syntax and semantics defined in RFC 7208 §4.
RFC Failure Mode: Unlike DMARC (where unknown tags are silently ignored per RFC 7489 §6.3), SPF with unrecognized mechanisms produces a PermError per RFC 7208 §4.6 — the record fails loudly rather than silently.
Related CVEs: CVE-2024-7208 (multi-tenant domain spoofing), CVE-2024-7209 (shared SPF exploitation), CVE-2023-51764 (SMTP smuggling bypasses SPF)
SPF hard fail (-all): compliance-strong, but can short-circuit DMARC. RFC 7489 notes that -all can cause some receivers to reject mail during the SMTP transaction — before DKIM is checked and before DMARC can evaluate the result. A message that would pass DMARC via DKIM alignment may be rejected prematurely. For most domains, ~all + DMARC p=reject is the strongest compatible posture — it allows every authentication method (SPF, DKIM, DMARC) to be fully evaluated before a decision is made.
DMARC enforcement is partial (quarantine). -all may preempt DKIM/DMARC evaluation at some receivers. Consider p=reject for full enforcement; ~all is more DMARC-compatible.

DMARC Policy RFC 7489 §6.3 Gold

Are spoofed emails rejected or quarantined? Quarantined, not rejected
Success p=quarantine

DMARC policy quarantine (100%) - good protection

v=DMARC1; p=quarantine; adkim=s
Alignment: SPF relaxed DKIM strict
No np= tag (DMARCbis) — non-existent subdomains inherit p= policy but adding np=reject provides explicit protection against subdomain spoofing
No aggregate reporting (rua) configured — you won't receive reports about authentication results and potential abuse
No forensic reporting (ruf) tag — this is correct. The absence of ruf= is not a gap. RFC 7489 §7.3 warns that forensic reports can expose PII (full message headers or bodies). Google, Microsoft, and Yahoo do not honour ruf= requests regardless. The DMARCbis draft (draft-ietf-dmarc-dmarcbis) has formally removed ruf= from the specification, confirming its deprecation. Omitting ruf= is the recommended modern practice. RFC 7489 §7.3 — Forensic Reports
RFC 7489 Present — DMARC record published per RFC 7489 §6.3.
Monitoring Posture Note: Quarantine sequesters authentication failures while preserving full DMARC forensic telemetry (RFC 7489 §7). Some organizations maintain quarantine rather than reject as a deliberate monitoring strategy — failed messages are processed and reported but sequestered from the inbox. See NIST SP 800-177 Rev. 1 for enforcement tradeoffs.
DMARCbis (Pending): draft-ietf-dmarc-dmarcbis will elevate DMARC to Standards Track, obsolete RFC 7489, replace pct= with t= (testing flag), add np= (non-existent subdomain policy), and mandate DNS tree walk for policy discovery instead of the Public Suffix List.
Related CVEs: CVE-2024-49040 (Exchange sender spoofing), CVE-2024-7208 (multi-tenant DMARC bypass)

DKIM Records RFC 6376 §3.6 Gold

Are outbound emails cryptographically signed? Yes — verified
Found 2048-bit

Found DKIM for 2 selector(s) with strong keys (2048-bit)

s1._domainkey 2048-bit Adequate
v=DKIM1; k=rsa; h=sha256; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4d/jridMLV9rZ/lBiDYA17BWKWIHnvLzCVGoFcOENqxLym8ro869rgp82mcxobr2kPyd+sfAS/REOoZ+pkf1wnyywQrf4r9i1O9Bnop4/WsRXTIfgKtaIOtwyhgsv9JH5KpxeQxHwl9CEHhqJuFJp808gbqRZt6PDp2YetB23EyJ5kp/jpn5/aCvVpC27+jnQH6NoYN8wNsC6cTSA1EhL1etUwJrZUwRtf8S2PIDJOm1/CUtc9a/d3sZk15LDtUUbODrQMrj5mzMzHPYp43MwLFRlvSa/O+xIx8esNxwnDa7PH6PZLB8lhtkY49/4ofKV5BQKMGmGmyn+rgYDHD8iwIDAQAB
s2._domainkey 2048-bit Adequate
v=DKIM1; k=rsa; h=sha256; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4d/jridMLV9rZ/lBiDYA17BWKWIHnvLzCVGoFcOENqxLym8ro869rgp82mcxobr2kPyd+sfAS/REOoZ+pkf1wnyywQrf4r9i1O9Bnop4/WsRXTIfgKtaIOtwyhgsv9JH5KpxeQxHwl9CEHhqJuFJp808gbqRZt6PDp2YetB23EyJ5kp/jpn5/aCvVpC27+jnQH6NoYN8wNsC6cTSA1EhL1etUwJrZUwRtf8S2PIDJOm1/CUtc9a/d3sZk15LDtUUbODrQMrj5mzMzHPYp43MwLFRlvSa/O+xIx8esNxwnDa7PH6PZLB8lhtkY49/4ofKV5BQKMGmGmyn+rgYDHD8iwIDAQAB
RFC 6376 Conformant — DKIM keys and signatures conform to RFC 6376 §3.6 (Internet Standard).
Known Vulnerabilities: DKIM l= tag body length vulnerability (attacker appends unsigned content to signed mail), weak key exploitation (keys below 1024-bit are cryptographically breakable per RFC 6376 §3.3.3), DKIM replay attacks (re-sending legitimately signed messages at scale)

MTA-STS RFC 8461 §3 Gold

Can attackers downgrade SMTP to intercept mail? No — TLS enforced
Success ENFORCE Policy Verified

MTA-STS enforced - TLS required for 1 mail server(s)

v=STSv1; id=20190723;
Policy Details:
  • Mode: enforce
  • Max Age: 1 days (86400 seconds)
  • MX Patterns: mail.tutanota.de

MTA-STS policy enforcement is evaluated in Mail Transport Security below.

TLS-RPT RFC 8460 §3 Gold

Will failures in TLS delivery be reported? Yes — reports configured
Success

TLS-RPT configured - receiving TLS delivery reports

v=TLSRPTv1;rua=mailto:mta-sts-reports@tutanota.com
02 Chain of authority · L1 Domain Security Can DNS answers and certificate issuance be trusted? DANE / TLSA CAA Delegation DNSSEC Operations DNSSEC & NS Protected
DANE / TLSA Gold Recon Methodology Can mail servers establish identity without a public CA? Yes
RFC 7672 §3 RFC 6698 §2 1/1 MX

DANE configured — TLSA records found for all 1 MX host

MX Host Usage Selector Match Certificate Data
mail.tutanota.de 3 DANE-EE (Domain-issued certificate) Full certificate SHA-256 d141f8f3a4aac2e4d2677aafcc723d8e5cc7b146e968c3aea348ed93996bbe6f
mail.tutanota.de 3 DANE-EE (Domain-issued certificate) Full certificate SHA-256 ae20396b8498eac32acecfdad63da655edbd6d6d79f7e1e0931852c8b738306d
Email Transport Security

Two mechanisms protect email in transit. DANE is the primary standard; MTA-STS is the alternative for domains that cannot deploy DNSSEC:

  • DNSSEC + DANE (RFC 7672) — Cryptographic chain of trust from DNS root to mail server certificate. Eliminates reliance on certificate authorities. No trust-on-first-use weakness. Requires DNSSEC.
  • MTA-STS (RFC 8461) — HTTPS-based policy requiring TLS for mail delivery. Works without DNSSEC but relies on CA trust and is vulnerable on first use (§10). Created for domains where “deploying DNSSEC is undesirable or impractical” (§2).
This domain deploys both DANE and MTA-STS — defense in depth. DANE provides cryptographic certificate binding via DNSSEC, while MTA-STS provides compatibility with senders that don't validate DNSSEC. Per RFC 8461, DANE takes precedence — MTA-STS must not override a failing DANE validation.

Industry trend: Microsoft Exchange Online enforces inbound DANE with DNSSEC (GA October 2024), and providers like Proton Mail and Fastmail also support DANE. Google Workspace does not support DANE and relies on MTA-STS. Both mechanisms coexist because DANE is backward-compatible — senders skip the check if the domain isn't DNSSEC-signed (RFC 7672 §1.3).

CAA RFC 8659 §4 Gold Success

Does this domain restrict who can issue TLS certificates? Yes

CAA configured - only Let's Encrypt, Sectigo can issue certificates

Authorized CAs: Let's Encrypt Sectigo
0 issue "letsencrypt.org"
0 issue "sectigo.com"
Since September 2025, all public CAs must verify domain control from multiple geographic locations (Multi-Perspective Issuance Corroboration, CA/B Forum Ballot SC-067). CAA records are now checked from multiple network perspectives before certificate issuance.
Delegation Consistency 1 Issue

Delegation consistency: 1 issue(s) found — Parent/child NS delegation alignment: DS↔DNSKEY, glue records, TTL drift, SOA serial sync.

Findings:
  • Could not retrieve NS TTL from parent zone

DS ↔ DNSKEY Alignment Aligned

DS Key TagDS AlgorithmDNSKEY Key TagDNSKEY Algorithm
47014 13 47014 13

Glue Record Completeness Complete

NameserverIn-BailiwickIPv4 GlueIPv6 GlueStatus
ns-1339.awsdns-39.org No N/A N/A OK
ns-1938.awsdns-50.co.uk No N/A N/A OK
ns-492.awsdns-61.com No N/A N/A OK
ns-660.awsdns-18.net No N/A N/A OK

NS TTL Comparison Drift

Child TTL: 600s Drift: 0s

SOA Serial Consistency Consistent

ns-1339.awsdns-39.org: 1
ns-1938.awsdns-50.co.uk: 1
ns-492.awsdns-61.com: 1
ns-660.awsdns-18.net: 1
DNSSEC Operations Deep Dive 1 Issue

DNSSEC operational notes: 1 item(s) to review — KSK/ZSK differentiation, RRSIG expiry windows, NSEC/NSEC3 analysis, and rollover readiness.

Findings:
  • Single KSK with no CDS/CDNSKEY automation — manual rollover required

DNSKEY Inventory 3 Keys

RoleKey TagAlgorithmKey Size
ZSK 38075 ECDSA P-256/SHA-256 256 bits
ZSK 50228 ECDSA P-256/SHA-256 256 bits
KSK 47014 ECDSA P-256/SHA-256 256 bits

RRSIG Signatures 0 Signatures

No RRSIG records found.

Denial of Existence none

No NSEC or NSEC3 records detected.

Rollover Readiness Not_ready

Multiple KSKs:
CDS Published:
CDNSKEY Published:
Automation: none
Domain Security Methodology Can DNS responses be tampered with in transit? No DNSSEC signed and validated, cryptographic chain of trust verified

DNSSEC RFC 4033 §2 Gold Signed ECDSA P-256/SHA-256 Modern

DNSSEC fully configured and validated — AD (Authenticated Data) flag set by resolver 8.8.8.8 confirming cryptographic chain of trust from root to zone (RFC 4035 §3.2.3)

Algorithm Observation: ECDSA P-256/SHA-256 — MUST implement, recommended default (RFC 8624 §3.1)
All current DNSSEC algorithms use classical cryptography. Post-quantum DNSSEC standards are in active IETF development (draft-sheth-pqc-dnssec-strategy) but no PQC algorithms have been standardized for DNSSEC yet.
Chain of trust: Root → TLD → Domain. DNS responses are cryptographically authenticated and tamper-evident.
AD Flag: Validated - Resolver (8.8.8.8) confirmed cryptographic signatures
DS Record (at registrar):
47014 13 2 B25B9B4FC9D805F1ED361B1EFA9B7BB8D2C105C8BBB1A002108547D1A19FF12B

NS Delegation Verified

4 nameserver(s) configured

Nameservers: ns-1339.awsdns-39.org ns-1938.awsdns-50.co.uk ns-492.awsdns-61.com ns-660.awsdns-18.net
Managed DNS
All 4 nameservers hosted by Amazon Route 53. Managed DNS provides reliable resolution with provider-maintained infrastructure.
DNS provider(s): Amazon Route 53
Multi-Resolver Verification Recon: Consensus reached - 5 resolvers (Cloudflare, Google, Quad9, OpenDNS, DNS4EU) agree on DNS records
03 Delivery path · L1 Transport Security Will mail transport resist downgrade and interception? STARTTLS MTA-STS policy TLS-RPT
Mail Transport Security Beta Is mail transport encrypted and verified? Yes Both MTA-STS and DANE enforce encrypted mail delivery

All 1 server(s) verified: encrypted transport confirmed via direct SMTP probe and DNS policy

Policy Assessment Primary
  • MTA-STS policy in enforce mode requires encrypted transport (RFC 8461)
  • DANE/TLSA records published — mail servers pin TLS certificates via DNSSEC (RFC 7672)
  • TLS-RPT configured — domain monitors TLS delivery failures (RFC 8460)
Telemetry
TLS-RPT configured — domain receives reports about TLS delivery failures from sending mail servers (RFC 8460)
Reporting to: mailto:mta-sts-reports@tutanota.com
Live Probe Supplementary
MX Host STARTTLS TLS Version Cipher Key Exchange Certificate
mail.tutanota.de TLSv1.3 TLS_AES_256_GCM_SHA384 N/A Valid
Expires: 2026-09-05 (184 days)
Issuer: Sectigo Limited
Multi-Vantage Probe Results
Unanimous: TLS verified 2 probes, 1 responded
France - EU observed
All servers support TLS
US-East (Boston) skipped
What Is Measured: Our probe’s TLS 1.3 handshake offers the hybrid post-quantum group X25519MLKEM768 (X25519 combined with ML-KEM-768). The Key Exchange column reports the group each mail server actually negotiated — direct, observed evidence of its post-quantum readiness toward a hybrid-capable client.
Quantum-Safe Hybrid: The session key agreement combines classical X25519 with ML-KEM-768, standardized in FIPS 203 (final, August 2024). This protects the key exchange against “harvest now, decrypt later” collection by a future quantum adversary.
Classical: The server completed the handshake without selecting the offered hybrid group. This is not a deviation — no RFC currently requires post-quantum key exchange. The X25519MLKEM768 group is defined in draft-ietf-tls-ecdhe-mlkem (Standards Track draft, not yet an RFC); the hybrid approach is described in draft-ietf-tls-hybrid-design (IESG-approved Informational). Servers supporting only other hybrid groups also read as Classical here.
Transition Outlook: NIST’s draft transition guidance (NIST IR 8547) projects quantum-vulnerable algorithms being deprecated after 2030 and disallowed after 2035. Hybrid key exchange requires TLS 1.3. This finding is informational and does not affect this domain’s grade.
04 Human-visible identity · L1 Brand & Trust Can this brand be convincingly faked? BIMI & VMC CAA · see Domain Security Not Setup
Brand Security Can this brand be convincingly faked? Likely DMARC quarantine flags but does not reject spoofed mail (RFC 7489 §6.3), and no BIMI brand verification — lookalike domains display identically in inboxes; CAA restricts certificate issuance (RFC 8659 §4) but visual brand faking remains open

BIMI BIMI Spec Gold