Email deliverability
Diagnose why a domain's email lands in spam: SPF posture, DMARC policy, DKIM key strength, MX targets, and a composite 0–100 score.
$0.10
per call · one payment for the whole workflow
POST /api/skill/email-deliverability
6 tools run server-side in one request. You pay once, settle once, and get a single response - no orchestration, no per-step payments, and a partial-success envelope if any step fails. USDC over x402 on any supported chain.
When to use this pack
Marketing or transactional email is landing in spam, or you're rolling out a new sending domain and want to verify the auth posture before the first campaign.
Tools in this pack
All 6 run inside the single $0.10 call above. Each is also callable on its own if you only need one part.
- SPF check POST /api/spf-check Fetch and validate a domain's SPF record (RFC 7208). Parses mechanisms (ip4/ip6/include/a/mx/all), counts DNS lookups against the famous 10-lookup limit, and flags the qualifier on `all` (-/fail, ~/softfail, ?/neutral). The first stop when an email is hitting the spam folder.
- DMARC check POST /api/dmarc-check Fetch and validate a domain's DMARC policy at _dmarc.<domain> (RFC 7489). Surfaces the enforcement policy (none/quarantine/reject), reporting addresses, alignment modes, and common misconfigs (no rua, p=none stuck for months, percent <100). Pair with SPF and DKIM for full Feb-2024 sender-rule compliance.
- DKIM key lookup POST /api/dkim-lookup Fetch and parse a DKIM public-key record at <selector>._domainkey.<domain> (RFC 6376). Returns the parsed key params (algorithm, length, flags) so you can verify rotation status or key strength. Caller must know the selector - use email-deliverability if you don't.
- Email deliverability check POST /api/email-deliverability End-to-end email-auth report for a domain: SPF + DMARC + DKIM (probes common selectors automatically) + MX records + score 0–100. The one call to make when 'why is our mail going to spam?' lands in your inbox.
- Email validate POST /api/email-validate Validate an email address: syntax check plus live MX record lookup on the domain (deliverability signal, not a guarantee).
- DNS lookup POST /api/dns-lookup Resolve any DNS record type for a host: A, AAAA, MX, TXT, CNAME, NS, SOA, CAA, SRV, PTR. Returns the records plus a count. Built on Node's native resolver - no external API.
Workflow
- Parse the SPF record - the tool flags the most common failures (>10 DNS lookups, +all permissive directive, syntax errors).
- Parse the DMARC policy - p=none means receivers ignore SPF/DKIM failures, which usually explains a 'we set it all up but it still goes to spam' problem.
- Probe 14 common DKIM selectors and warn on <1024-bit keys and testing-mode (t=y) records. Most sending platforms publish under a predictable selector this catches.
- Run the composite deliverability score (25 points each for SPF + DMARC + DKIM + MX) for a single integer to report back to the team.
- Validate a single recipient address with email-validate to confirm the MX is actually reachable.
- Spot-check the MX records with dns-lookup type=MX to verify the chain matches the sending platform's documented setup.
Call it directly
Any x402 client pays the 402 and gets the whole workflow back in one response:
npx agent402-client call email-deliverability {"domain":"example.com"}
Run it in Claude
claude mcp add agent402 -s user -- npx -y agent402-mcp@latest
Then paste this prompt into Claude:
Diagnose email deliverability for sender@example.com. Use Agent402 to check SPF, DMARC, DKIM (probe common selectors), and the composite email-deliverability score. If the score is below 75, explain which auth records are missing or weak and how to fix each one.