{
  "id": "communication/smtp-554-5-7-0-relay-denied",
  "signature": "554 5.7.0 Relay access denied",
  "signature_zh": "554 5.7.0 中继访问被拒绝",
  "regex": "554.*5\\.7\\.0.*Relay access denied|Relay access denied",
  "domain": "communication",
  "category": "auth_error",
  "subcategory": null,
  "root_cause": "SMTP server rejects the relay attempt because the client's IP or authenticated user is not authorized to send emails to external domains.",
  "root_cause_type": "generic",
  "root_cause_zh": "SMTP 服务器拒绝中继尝试，因为客户端 IP 或认证用户无权向外部域发送邮件。",
  "versions": [
    {
      "version": "Postfix 3.7.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Exim 4.96",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Sendmail 8.17.1",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "Disable SMTP authentication on the server to allow open relay",
      "why_fails": "Open relays are a security risk and will be blacklisted; also violates RFC requirements.",
      "fail_rate": 0.95,
      "condition": "",
      "sources": []
    },
    {
      "action": "Change the sender email address to a local domain on the server",
      "why_fails": "The relay denial is based on the recipient domain, not the sender; local sender still fails for external recipients.",
      "fail_rate": 0.7,
      "condition": "",
      "sources": []
    },
    {
      "action": "Increase the SMTP timeout value",
      "why_fails": "The error is an authorization failure, not a timeout; timeout changes don't affect relay permissions.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Add the client's IP to the relay allow list in the SMTP server config: For Postfix, add to `/etc/postfix/main.cf`: `mynetworks = 192.168.1.0/24` and restart with `systemctl restart postfix`.",
      "success_rate": 0.85,
      "how": "Add the client's IP to the relay allow list in the SMTP server config: For Postfix, add to `/etc/postfix/main.cf`: `mynetworks = 192.168.1.0/24` and restart with `systemctl restart postfix`.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Enable SMTP authentication with valid credentials: In the client, configure `smtp_auth = login` and provide a username/password that has relay rights. For Python's smtplib, use `server.login(user, password)`.",
      "success_rate": 0.9,
      "how": "Enable SMTP authentication with valid credentials: In the client, configure `smtp_auth = login` and provide a username/password that has relay rights. For Python's smtplib, use `server.login(user, password)`.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Route email through a dedicated relay service like SendGrid or AWS SES with proper SPF/DKIM records.",
      "success_rate": 0.8,
      "how": "Route email through a dedicated relay service like SendGrid or AWS SES with proper SPF/DKIM records.",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Add the client's IP to the relay allow list in the SMTP server config: For Postfix, add to `/etc/postfix/main.cf`: `mynetworks = 192.168.1.0/24` and restart with `systemctl restart postfix`.",
    "Enable SMTP authentication with valid credentials: In the client, configure `smtp_auth = login` and provide a username/password that has relay rights. For Python's smtplib, use `server.login(user, password)`.",
    "Route email through a dedicated relay service like SendGrid or AWS SES with proper SPF/DKIM records."
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://www.ietf.org/rfc/rfc2821.txt",
  "official_doc_section": null,
  "error_code": "554",
  "verification_tier": "ai_generated",
  "confidence": 0.87,
  "fix_success_rate": 0.8,
  "resolvable": "true",
  "first_seen": "2023-09-05",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}