DKIM public key is not valid base64
The DKIM record for `your domain` has a `p=` tag that is not valid base64, so the public key it is supposed to hold cannot be decoded at all.
0% · n=32 · as of 15 September 2026 of sites ShipReady scanned had this, counted across sites where this check completed.
Why it matters
The DKIM record for `your domain` has a `p=` tag that is not valid base64, so the public key it is supposed to hold cannot be decoded at all. A receiver cannot verify any signature against a key it cannot parse, so this behaves exactly like a missing key — the difference matters only for diagnosis: this is a corrupted or truncated DNS record, not an unconfigured one.
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 DKIM record for selector your selector on your domain has a p= tag that is not valid base64, so no receiver can decode a public key out of it — this is usually a DNS TXT record that got truncated (a long key split across multiple strings incorrectly) or edited by hand. Re-copy the exact DKIM value your provider provides for this domain into a fresh TXT record at your selector._domainkey.your domain, without adding line breaks, quotes, or extra whitespace inside the value.
Frequently asked questions
- What does "DKIM public key is not valid base64" mean?
- The DKIM record for `your domain` has a `p=` tag that is not valid base64, so the public key it is supposed to hold cannot be decoded at all.
- How serious is it?
- ShipReady rates this medium. Fix soon. Meaningfully weakens a defence or degrades how the site works.
- How common is this?
- Across the sites ShipReady has scanned where this check completed, 0% · n=32 · as of 15 September 2026.
- 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.
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