Claw0x Validate Email

Email Validator

Check whether an email address is properly formatted and assess its risk level. Pure server-side logic — no external API dependency.

Free to use. This skill costs nothing. Just sign up at claw0x.com, create an API key, and start calling. No credit card, no wallet top-up required.

How It Works — Under the Hood

This skill runs entirely as deterministic server-side logic. No LLM, no third-party verification API. It performs a multi-step validation pipeline on the email string you provide:

Step 1: Format Validation (RFC 5322)

The email is checked against the RFC 5322 standard for email address syntax:

• Local part (before @): must be 1–64 characters, allows alphanumeric, dots, hyphens, underscores, and plus signs. Cannot start or end with a dot, and cannot have consecutive dots.
• Domain part (after @): must be a valid hostname — alphanumeric labels separated by dots, each label 1–63 characters, TLD at least 2 characters.
• Total length: 3–254 characters per the SMTP spec.

Step 2: Domain Extraction & Analysis

The domain is extracted and analyzed for known risk signals:

• Disposable email providers — domains like mailinator.com, guerrillamail.com, tempmail.com and ~50 others are flagged as high-risk. These are commonly used for spam signups and throwaway accounts.
• Free email providers — domains like gmail.com, yahoo.com, outlook.com are noted but not penalized. They're legitimate but less trustworthy for B2B contexts.
• Corporate domains — custom domains (e.g. user@company.com) are considered lower risk.

Step 3: Risk Scoring

A numeric risk score (0–100) is computed based on weighted factors:

Lower score = safer email. The score is a heuristic, not a deliverability guarantee — it tells you how likely the email is to be legitimate based on structural analysis alone.

What This Skill Does NOT Do

• No SMTP verification — it doesn't connect to the mail server to check if the mailbox exists. This would require network calls, introduce latency, and risk IP blacklisting.
• No DNS MX lookup — it doesn't verify that the domain has mail exchange records. This keeps the skill fast and deterministic.
• No deliverability prediction — it can't tell you if an email will bounce. For that, you'd need a dedicated deliverability service.

This is by design. The skill is optimized for speed, determinism, and zero external dependencies — making it ideal as a pre-filter in agent pipelines before more expensive verification steps.

Prerequisites

This is a free skill. Just get an API key:

1. Sign up at claw0x.com
2. Go to Dashboard → API Keys → Create Key
3. Set it as an environment variable:

export CLAW0X_API_KEY="your-api-key-here"

No credit card or wallet balance needed.

When to Use

• User says "validate this email", "is this email real", "check this email address"
• Agent pipeline needs to verify email inputs before sending
• Pre-filtering signups or form submissions for obvious junk
• Assessing email quality or risk in a data cleaning pipeline

Input

Output Fields

Example

Input: "test@mailinator.com"

Output:

{
  "valid": true,
  "email": "test@mailinator.com",
  "checks": {
    "format_valid": true,
    "domain": "mailinator.com",
    "local_part": "test"
  },
  "risk_score": 80,
  "suggestion": null
}

Format is valid, but risk score is high (80) because mailinator.com is a known disposable email provider.

Error Codes

• 400 — Missing or invalid email input
• 401 — Invalid or missing API key
• 500 — Processing failed (not billed)

Pricing

Free. Apply for an API key and use it at no cost. No credit card required.