Email Deliverability at Risk: SPF, DKIM, and DMARC Misconfigurations Cause Business Mail to Land in Spam
What Happened — A ZDNet Security article explains that many organizations still lack proper SPF, DKIM, and DMARC DNS records, resulting in legitimate business emails being relegated to recipients’ spam folders and exposing domains to spoofing attacks.
Why It Matters for TPRM —
- Undelivered or mis‑routed communications can disrupt critical business processes and vendor coordination.
- Spoofed emails originating from a partner’s domain can be used for phishing, BEC, or credential theft, expanding the attack surface of the supply chain.
- Regulatory frameworks (e.g., GDPR, HIPAA) consider email integrity a control; non‑compliance may trigger audit findings.
Who Is Affected — All industries that rely on corporate email (technology SaaS, finance, healthcare, retail, professional services, etc.) and any third‑party vendors that send bulk or transactional mail on behalf of their customers.
Recommended Actions —
- Inventory all domains used by third‑party vendors for outbound email.
- Verify that SPF, DKIM, and DMARC records are published and aligned with vendor‑provided sending IPs.
- Enforce a “reject” DMARC policy for domains that fail authentication and monitor aggregate reports.
- Incorporate email‑auth health checks into vendor risk assessments and continuous monitoring programs.
Technical Notes —
- SPF validates authorized sending IPs via a DNS TXT record.
- DKIM adds a cryptographic signature to each message, ensuring integrity in transit.
- DMARC ties SPF/DKIM results together, publishing a policy (none/quarantine/reject) and providing forensic/aggregate reports.
- Major providers (Gmail, Yahoo, Outlook.com) now require all three for bulk senders (enforced since Feb 2024 for Gmail/Yahoo, May 2025 for Microsoft).
Source: ZDNet Security – How I got my business emails through spam filters with SPF, DKIM, and DMARC