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 5,242,611+ 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

Google and Yahoo Bulk Sender Requirements: A Practical Checklist

The short answer (what's causing it)

Gmail and Yahoo require senders — especially those sending around 5,000+ messages a day to their users, per Google's published guidance — to authenticate properly and make unsubscribing easy. Missing items lead to deferrals (421 4.7.x) or rejections (550 5.7.26).

Step-by-step fix

  1. SPF and DKIM pass for your sending domain.
  2. DMARC record published (minimum p=none) and aligned with SPF or DKIM.
  3. Valid forward and reverse DNS (PTR) for sending IPs; TLS for transmission.
  4. Marketing mail carries List-Unsubscribe and List-Unsubscribe-Post: List-Unsubscribe=One-Click headers; unsubscribes honoured within 2 days.
  5. Keep the spam rate reported in Google Postmaster Tools low (Google cites staying below 0.3%).
  6. Re-scan with the free tool after each change.

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

_dmarc.example.co.uk. TXT "v=DMARC1; p=none; rua=mailto:[email protected]"
List-Unsubscribe: <https://example.co.uk/unsub?u=123>, <mailto:[email protected]>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

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

Check yours free in seconds

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

Scan my domain free (20-check SuperTool) → £5 Website Launch Special Quick-Fix Pack →

One-off download via PayPal guest checkout, no subscription. Packs contain DNS/config templates and scripts you run yourself.

Frequently Asked Questions

Do the rules apply if I send under 5,000 a day?

SPF or DKIM, PTR and low spam rates apply to all senders; the full set is mandatory for bulk senders.

Does transactional mail need one-click unsubscribe?

Google's guidance applies it to marketing/subscribed messages, not receipts or password resets.

Related FaultyPacket guides & tools

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