> ## Documentation Index > Fetch the complete documentation index at: https://docs.vouch.expert/llms.txt > Use this file to discover all available pages before exploring further. # Validation Overview > Overview of validation types in Vouch ## Email Validation Strategy Vouch performs multiple validation checks on every email address to ensure comprehensive fraud detection and email quality assurance. Each validation type can be individually configured to either **allow**, **flag**, or **block** based on your requirements. ## Validation Categories ### Email Format Validation These checks verify the email address itself is valid and deliverable: Ensures the email conforms to RFC 5322 standards. This is the most basic check that catches obvious typos and malformed addresses. **Common failures:** * Missing @ symbol * Invalid characters * Malformed domain * Missing local or domain part Verifies that the email domain has valid mail exchange (MX) records configured in DNS. Without MX records, the domain cannot receive emails. **What it checks:** * DNS MX record existence * At least one valid mail server * Proper DNS configuration ### Quality & Risk Detection These checks identify potentially problematic or risky email addresses: Identifies temporary email services like Mailinator, Guerrilla Mail, or 10minutemail. These are often used for spam, fraud, or to avoid long-term commitment. Detects generic organizational emails like admin@, support@, or info@ rather than personal email addresses. Identifies plus-addressing ([user+tag@domain.com](mailto:user+tag@domain.com)) which allows one email address to create unlimited variations. ### Fraud & Device Detection These checks identify patterns associated with fraudulent behavior: Creates a unique fingerprint of the user's device to track it across multiple signups. Detects when the same device is used to create many accounts. Analyzes the user's IP address to detect VPNs, Tor networks, proxies, data centers, and known fraudulent IPs. ### Configuration per Check Each validation type can be configured independently: | Action | Behavior | When to Use | | --------- | -------------------------------------------- | ------------------- | | **ALLOW** | Check runs but doesn't affect recommendation | Gathering data only | | **FLAG** | Failure marks email as suspicious | Review recommended | | **BLOCK** | Failure immediately blocks email | Critical checks | ## Validation Response Structure Each validation returns a consistent structure with the following fields: ### Field Definitions Whether the check passed (true) or failed (false) The configured action for this check: `allow`, `flag`, or `block` Human-readable description of the result Additional fields vary by validation type and provide specific details about what was detected. ## Recommendation Logic The final recommendation is determined by aggregating all validation signals. If any BLOCK-configured check fails, the recommendation is "block". If any FLAG-configured check fails, the recommendation is "flag". Otherwise, the recommendation is "allow". ### Recommendation Values Email passed all checks. Safe to proceed with account creation. Suspicious signals detected. Consider manual review or additional verification. Critical validation failed. Reject this email address. ## Default Configuration By default, Vouch uses this configuration: | Validation | Default Action | Rationale | | ------------------ | -------------- | ------------------------------------ | | Syntax | BLOCK | Invalid format cannot receive email | | Disposable | BLOCK | Temporary emails indicate fraud | | MX Records | BLOCK | No mail server means undeliverable | | Role Email | ALLOW | Often legitimate but worth tracking | | Alias | FLAG | Can indicate multi-accounting | | Device Fingerprint | FLAG | Multiple accounts may be legitimate | | IP Reputation | FLAG | VPNs used legitimately by some users | \*Begin with more checks set to FLAG rather than BLOCK. Review flagged accounts to understand your user base before tightening restrictions. ## Next Steps Learn about email format validation Understand temporary email detection Deep dive into fraud detection Learn about threat detection