superagent_

// context guardrails

Email

Score a raw RFC 822 email before an agent trusts the sender, body, attachments, or links.

Score a raw RFC 822 / .eml message before an agent reads it, summarizes it, or follows links inside it.

How scoring works

An email scan runs in three tiers:

  1. Identity — From domain RDAP/TLS/blocklists, SPF/DKIM/DMARC from Authentication-Results, display-name mismatch, and Reply-To divergence. A blocklisted sender short-circuits to score 0.
  2. Body and attachments — prompt injection, exfiltration, urgency, brand impersonation, hidden HTML, encoded payloads, and dangerous attachment types. Up to eight public https links are followed with the web-page scanner.
  3. LLM review — always runs unless the sender is blocklisted. Looks for phishing, brand impersonation, and hidden agent instructions.

The raw message is not stored on the artifact. Cache lookup uses the SHA-256 of the raw bytes. Invalid identifiers or RFC 822 bodies return 400 invalid_request. Unknown email identifiers return 404 not_found.

Threats

When details=true or the verdict is suspicious / dangerous, email scans may emit spf_fail, display_name_mismatch, brand_impersonation, malicious_attachment, phishing, and prompt-injection or exfiltration types shared with other origins.

Use it

  • Dashboard: open Agents → Context, paste a raw message, and open the result for identity, behavior, and content scores.
  • REST API: POST /api/v1/context/email to score raw email and GET /api/v1/context/email/{identifier} to look up a previous result. See the Context Guardrails API.
  • Resend: scan inbound mail from a receiving domain. See Resend.
  • Bird: handle email.received, fetch the stored raw RFC 5322 message, and run the full email scan. See Bird.
  • MCP: scan_email.

Submit an email

Use Content-Type: message/rfc822 or text/plain. Raw bodies larger than 1 MB are rejected.

curl "https://superagent.sh/api/v1/context/email?details=true" \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: message/rfc822" \
  --data-binary @message.eml
curl "https://superagent.sh/api/v1/context/email/<sha256>?details=true" \
  -H "Authorization: Bearer sk_live_..."

To rescan an email, POST the raw body again. GET never starts a new scan.

Next steps