DMARC policy applies to only part of your mail (pct < 100)
The DMARC record on `your domain` enforces `p=quarantine or reject` but with `pct=less than 100`, so only less than 100% of messages that fail authentication are subject to that policy — the rest are handled as if the policy were one level weaker (reject falls back to quarantine, quarantine falls back to doing nothing).
Why it matters
The DMARC record on `your domain` enforces `p=quarantine or reject` but with `pct=less than 100`, so only less than 100% of messages that fail authentication are subject to that policy — the rest are handled as if the policy were one level weaker (reject falls back to quarantine, quarantine falls back to doing nothing). `pct` exists to ramp up enforcement gradually; a value left below 100 indefinitely means part of the forged mail your policy was meant to stop keeps getting through.
How ShipReady detects it
Email-authentication DNS records (DMARC / SPF). Almost every AI-built SaaS sends transactional email — password resets, magic links, receipts — through Resend, SendGrid or Postmark. Setting that up gets the mail delivered; it does not stop anyone else sending mail that claims to come from the same domain. Without a DMARC policy, a receiving server has no instruction to reject a forgery, so an attacker can send "reset your password" from the product's own domain and the message will land in the inbox looking authentic. This check is almost entirely DNS rather than HTTP — one exception is MTA-STS, whose policy is only half-published in DNS; the other half is a file fetched over HTTPS (see _check_mta_sts). Nearly everything else here is the most deterministic kind of check the scanner has: a record either exists or it does not, so there is no heuristic and no false-positive surface. The one place judgement is required is deciding WHICH domain to ask about — see _organizational_domain.
Detection is deterministic. ShipReady reports this only when it observes the condition directly, and prefers to miss a real problem over inventing one. Rule version 1.10.0.
How to fix it
This is the prompt ShipReady puts in your report — written to be pasted straight into Cursor, Claude Code, or whichever assistant built the app.
The DMARC record on your domain enforces p=quarantine or reject but only for pct=less than 100% of failing mail — the rest is treated as one level weaker. This is meant as a temporary ramp-up step. If your DMARC aggregate reports (rua=) show no legitimate mail failing alignment, remove the pct= tag entirely (it defaults to 100) or set it explicitly to pct=100 so the policy applies to all failing mail, not just a sample.
Frequently asked questions
- What does "DMARC policy applies to only part of your mail (pct < 100)" mean?
- The DMARC record on `your domain` enforces `p=quarantine or reject` but with `pct=less than 100`, so only less than 100% of messages that fail authentication are subject to that policy — the rest are handled as if the policy were one level weaker (reject falls back to quarantine, quarantine falls back to doing nothing).
- How serious is it?
- ShipReady rates this low. Worth fixing. Small individually, and they accumulate.
- How do I fix it?
- Paste the fix prompt on this page into Cursor, Claude Code or your AI editor. It is the same prompt ShipReady puts in your report.
- Can I check my own site?
- Yes — ShipReady scans up to ten pages of any public site for free and reports this alongside every other check. The free report lists every issue it finds and shows full evidence and a fix prompt for the critical and high-severity ones; medium and low findings are counted and unlock on Pro.
Related checks
Run this check on your site
ShipReady checks this and 193 other things across up to ten pages of your site, with an AI-ready fix for each. Free, no signup.