✉️✅ Email Authentication (email-auth)

SPF • DKIM • DMARC • BIMI • MTA-STS/TLS-RPT • DANE — With Evidence

Email Authentication stops spoofing and brand abuse by proving who can send for your domains and how receivers should treat failures.
SolveForce builds email-auth as a system: SPF & DKIM alignment → DMARC enforcement → BIMI trust marks → MTA-STS/TLS-RPT (and DANE where viable) — wired to SIEM/SOAR so you can measure and prove protection.

📞 (888) 765-8301
✉️ contact@solveforce.com

Related pages:
🔐 Email Security → /email-security • 👤 IAM → /iam • 📊 Evidence/Automation → /siem-soar

🎯 Outcomes (Why this matters)

  • Spoofing blocked— receivers can quarantine/reject unauth mail for your domains.
  • Brand trust up— BIMI/DMARC alignment improves inbox presence and reduces phishing.
  • Deliverability stable— clear auth + TLS reduces false positives and transport failures.
  • Audit-grade proof— DMARC, TLS-RPT, and SIEM dashboards show alignment, failures, and enforcement.

🧭 Scope (What we build & operate)

  • SPF— curated include: chains, flattening where needed, parked domains with -all.
  • DKIM— per-sender selectors, 2048-bit keys (where supported), rotation cadence.
  • DMARC— enforcement roadmap (monitor → quarantine → reject), strict alignment (as policy allows), aggregate/forensic reporting.
  • BIMI— SVG logo + VMC issuance, DNS records, and alignment checks.
  • Transport auth— MTA-STS policy & TLS-RPT mailbox; optional DANE (TLSA) where DNSSEC is deployed.
  • ARC/Forwarding— ARC handling for forwarders/lists to retain DMARC benefits.
  • Evidence & alerts— DMARC XML pipeline → human-readable analytics → SIEM/SOAR alerts. → /siem-soar

🧱 Building Blocks (Spelled Out)

SPF (Sender Policy Framework)

  • Keep < 10 DNS lookups (RFC limit); collapse vendors via managed includes or flattening.
  • Use per-subdomain SPF when vendors send only for specific subs (e.g., news.example.com).
  • Parked domains: publish v=spf1 -all, A/MX removed or locked down.

DKIM (DomainKeys Identified Mail)

  • Sign from each sending platform with distinct selectors (e.g., mktg2025, svc2025).
  • Prefer rsa2048 keys; rotate 90–180 days; never reuse selectors across vendors.
  • Ensure aligned From: domain (or subdomain as policy).

DMARC

  • Start: p=none; rua=mailto:dmarc@…; ruf=…; fo=1 (monitor).
  • Enforce: phase to p=quarantine → p=reject with pct= ramp and per-subdomain records.
  • Tighten alignment: adkim=s; aspf=s (strict) where feasible.
  • Subdomain policy: sp=reject to cover all child domains.
  • Evidence: DMARC XML → analytics → SIEM (failures by source, alignment score). → /siem-soar

BIMI (Brand Indicators for Message Identification)

  • Publish BIMI TXT with SVG Tiny PS logo + Verified Mark Certificate (VMC) (per mailbox provider rules).
  • Requires DMARC enforcement (quarantine/reject) and high alignment.

MTA-STS / TLS-RPT (and DANE)

  • Enforce TLS for SMTP with MTA-STS policy (mta-sts.example.com + _mta-sts TXT).
  • Collect TLS-RPT at tlsrpt@… to spot downgrade attacks/misconfig.
  • If DNSSEC is deployed, consider DANE (TLSA) for SMTP servers.

ARC (Authenticated Received Chain)

  • Sign ARC headers on outbound (if you operate relays) and validate on inbound to preserve DMARC through forwarding lists.

🧰 Deployment Patterns (Choose Your Fit)

A) Core corporate domain + parked domains

  • SPF curated + DKIM per sender → DMARC monitor → reject; parked domains -all, sp=reject, wildcard MX null.

B) Multi-vendor marketing & billing

  • Dedicated subdomains (news., billing.) each with own SPF/DKIM; parent DMARC sp=reject; BIMI on primary only.

C) SaaS-first org

  • Inventory senders via DMARC reports; enable DKIM for each SaaS; collapse SPF includes; MTA-STS on core; TLS-RPT to SIEM.

D) High-trust brand (BIMI + VMC)

  • DMARC p=reject + strict alignment; SVG/VMC issuance; logo governance; TLS enforcement; ARC-friendly relays.

E) Government/regulated

  • DNSSEC + DANE (where accepted), MTA-STS required, strict DMARC, forensic reporting, SIEM/SOAR alerts into IR playbooks. → /incident-response

📐 SLO Guardrails (Targets You Can Measure)

KPI / SLOTarget (Recommended)
DMARC enforcementp=reject within 60–90 days
Alignment rate (SPF or DKIM aligned)≥ 98–99% of outbound volume
SPF DNS lookups≤ 8 (hard limit 10)
DKIM key length / rotation2048-bit, rotate 90–180 days
Subdomain policysp=reject for parent domain
TLS coverage (in/out)= 100% (MTA-STS enforced)
DMARC failure reduction (30d)≥ 90% vs baseline monitoring phase
BIMI readinessDMARC enforced + VMC issued
Evidence delivery to SIEM≤ 120 s (DMARC/TLS-RPT parsed)

SLO breaches auto-open tickets and trigger SOAR (disable sender, update SPF/DKIM, tighten DMARC pct/sp, fix TLS). → /siem-soar

📊 Observability & Evidence

  • DMARC analytics— aligned vs unaligned sources, top failing IPs/vendors, forwarder/ARC paths.
  • TLS-RPT— per-destination TLS success/failure, downgrade attempts, cipher posture.
  • Change logs— DNS record diffs (SPF/DKIM/DMARC/MTA-STS/BIMI); DKIM rotation history.
  • SIEM dashboards— alignment score, spoof attempts blocked, BIMI coverage, TLS health; exportable for audits. → /siem-soar

🛠️ Implementation Blueprint (No-Surprise Rollout)

1) Inventory senders — parse 30–45 days of DMARC reports to list all platforms; map to subdomains.
2) Harden SPF — prune/flatten; vendor-specific subdomain SPF; parked domains -all.
3) Enable DKIM everywhere — unique selectors per platform; publish keys; test signing & alignment.
4) Roll DMARC — p=none → quarantine → reject with pct= ramp; set sp=reject; tighten adkim/aspf as feasible.
5) Transport auth — publish MTA-STS; set TLS-RPT mailbox; (optional) DNSSEC + DANE.
6) BIMI — prepare SVG + VMC; publish BIMI TXT after DMARC enforcement.
7) ARC & forwarding — validate ARC; tune policies for list servers/forwarders.
8) Automate evidence — DMARC/TLS-RPT → parser → data store → SIEM; alerts & monthly reports.
9) Operate — quarterly DKIM rotation; SPF cleanup on vendor changes; review DMARC failures weekly; renew VMC annually.

✅ Pre-Engagement Checklist

🔤 Domains & subdomains list; DNS host (with API).
📨 Current senders (SaaS, marketing, billing, ticketing, CRM, relays).
🧾 DMARC report mailbox & parser target; TLS-RPT mailbox.
🔐 DNSSEC status; willingness to deploy DANE.
🖼️ Brand assets (SVG) and VMC CA preference for BIMI.
📊 SIEM endpoint & alerting channels; reporting cadence.
🗓️ Rotation cadences (DKIM, VMC), change window policy.

🔄 Where Email-Auth Fits (Recursive View)

1) Grammar — email flows traverse /connectivity and clients’ device posture from /mdm//mdr-xdr.
2) Syntax — identity & policy via /iam; domain trust via SPF/DKIM/DMARC/BIMI; transport via MTA-STS/TLS/DANE.
3) Semantics — /cybersecurity preserves truth; /siem-soar proves it.

📞 Enforce Email Authentication That Blocks Spoofing & Builds Trust

📞 (888) 765-8301
✉️ contact@solveforce.com

Key terms in plain language

Open a term for a concise explanation of language used on this page.

Software as a Service (SaaS)

Software accessed as an online service instead of being installed and maintained entirely on the customer’s own computers or servers.

Cybersecurity

The practices and controls used to protect identities, devices, networks, applications, and data from unauthorized access, disruption, or manipulation.

Identity and Access Management (IAM)

The systems and policies that determine who a user is, what resources they may access, and how that access is authenticated and reviewed.

MDR / XDR

Security services and tools that monitor activity, investigate suspicious behavior, and help contain threats. MDR is managed detection and response; XDR correlates signals across multiple security layers.

API

An application programming interface is a defined way for software systems to exchange data or request functions from one another.

Cloud Computing

Computing resources—such as applications, servers, storage, or databases—delivered from remote infrastructure and scaled as requirements change.