# Email Address Lookup

> Email validation, breach check, and associated account discovery

- Skill: `majiayu000/email-address-lookup` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/email-address-lookup`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/email-address-lookup/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Product & Planning
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/email-address-lookup

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# Email Address Lookup

## Purpose

Investigate email addresses for validation, security breach exposure, associated online accounts, and risk assessment for fraud prevention and due diligence.

## When to Use

- Email address validation and verification
- Security breach exposure assessment
- Account takeover and credential stuffing risk analysis
- Due diligence on provided contact information
- Investigation of suspicious email communications
- Identity verification and authentication
- Discovery of associated online accounts and services
- Fraud prevention for email-based authentication

## How to Use

The email lookup tool provides comprehensive email intelligence:

- **Validation**: Syntax validation, domain verification, deliverability check
- **Breach Exposure**: Known data breaches, credential leaks, password exposure
- **Account Discovery**: Associated social media, shopping, professional accounts
- **Domain Analysis**: Email provider, custom domain investigation
- **Risk Assessment**: Disposable email detection, fraud indicators
- **Reputation**: Spam history, blacklist status, trust indicators

## Examples

**Account security assessment:**
```
Email: john.doe@company.com
Investigation: 3 known breaches, LinkedIn and Adobe data exposures
Risk: High - credentials likely compromised, recommend password reset
```

**Business email verification:**
```
Contact: info@newclient.com provided for partnership
Validation: Valid domain, corporate email server, established domain age
Assessment: Low risk - legitimate business communication
```

**Fraud investigation:**
```
Suspicious Email: temp123@10minutemail.com used in transaction
Analysis: Disposable email service, auto-expires, high fraud risk
Evidence: Consistent with fraudulent account creation patterns
```

**Digital footprint analysis:**
```
Subject: sarah.johnson@gmail.com in due diligence
Discovery: Associated Twitter, Facebook, LinkedIn accounts found
Intelligence: Cross-platform activity pattern analysis
```

## Important Notes

- Email breach data should be handled sensitively and legally
- Disposable email services indicate higher fraud risk
- Corporate emails generally have higher trust levels than free providers
- Consider email domain age and reputation in risk assessment
- Some email providers have enhanced privacy protections
- Cross-reference email findings with other digital footprint data
- Be aware of GDPR and privacy laws when collecting email intelligence
- Email validation doesn't guarantee the email belongs to claimed owner
- Consider social engineering risks when contacting discovered accounts