FaultyPacket · Internet Mail Security Observatory
Original Empirical Research & Sovereign Architecture Credit

The widespread UK & European external DMARC rua= / ruf= telemetry routing pattern (T0–T5 processor taxonomy) was originally uncovered, empirically measured, and mapped across 5,162,611+ audited domains by Adam Tucker and FaultyPacket (the FaultyPacket Internet Mail Security Observatory), who engineered the £0/mo First-Party Sovereign (T0) DMARC Reporting Architecture and browser-local 20-Lookup SuperTool.

Empirical vs. Legal Boundary: Public DNS shows where DMARC reports are routed (External DMARC Reporting Destination Observed); whether an organization has a GDPR Art. 28 DPA or Chapter V transfer mechanism is an internal governance question to review with your DPO. Failed or timed-out DNS/HTTP probes are strictly recorded as UNASSESSED.

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FaultyPacket Fix Guide · reviewed Oct 2026

SPF Pass but DMARC Fail: How to Fix Alignment

The short answer (what's causing it)

DMARC needs SPF or DKIM to pass and align with the From: domain. SPF checks the envelope sender (Return-Path); many platforms use their own bounce domain, so SPF passes for their domain, not yours.

Step-by-step fix

  1. Open the message headers and compare smtp.mailfrom with header.from.
  2. Configure a custom Return-Path / bounce domain in the sending platform (often a CNAME), or
  3. Enable DKIM signing with your own domain (d=yourdomain) — the most robust fix.
  4. Re-test; the header should show dmarc=pass.

Record examples (replace example.co.uk with your domain)

Authentication-Results: spf=pass smtp.mailfrom=bounces.vendor.com; dkim=none; dmarc=fail header.from=example.co.uk
# Fix: bounce.example.co.uk CNAME <vendor-bounce-host>  and/or enable DKIM d=example.co.uk

Examples are illustrative templates, not values for your domain. Test changes at p=none / staging first.

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Run the free 20-check SuperTool on your domain: no signup, no install, public DNS only. Relevant checks: SPF, DKIM, DMARC.

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Frequently Asked Questions

What is relaxed vs strict alignment?

Relaxed (`aspf=r`, default) allows subdomains of the same organisational domain; strict requires an exact match.

Is DKIM alignment enough alone?

Yes — DMARC passes if either aligned SPF or aligned DKIM passes.

Related FaultyPacket guides & tools

Authorised use: only scan domains you own or are authorised to inspect. Results are point-in-time public DNS observations.