EnterpriseEmailValidator 1.0.3

📧 EmailValidator

Lightweight, high-performance email validation library for .NET.

This package validates email addresses using:

• ✔ RFC-compliant syntax validation
• ✔ IDN (International Domain Name) support
• ✔ MX record lookup (via DnsClient)
• ✔ A-record fallback check
• ✔ Role-based email detection
• ✔ Thread-safe mail server caching

Designed for backend services, APIs, SaaS platforms, and enterprise systems that need reliable email validation beyond simple regex checks.

✨ Features

1️⃣ Syntax Validation

• RFC-compliant email format validation
• Local-part length enforcement (max 64 chars)
• Domain length enforcement (max 255 chars)
• Unicode domain normalization using IdnMapping

2️⃣ Role-Based Email Detection

Prevents use of common role-based addresses such as:

• admin@
• support@
• info@
• sales@
• contact@
• billing@
• postmaster@
• webmaster@
• noreply@
• security@

3️⃣ Mail Server Verification

Uses DnsClient to verify that the domain can receive email:

• MX record lookup
• A record fallback if no MX exists
• Thread-safe caching of lookup results
• Configured DNS timeout and retry control

4️⃣ Thread-Safe Performance

• Uses ConcurrentDictionary for DNS caching

• DNS client configured with:

  • 5-second timeout
  • 1 retry
  • Internal DNS caching enabled

• Safe for high-concurrency environments

📦 Installation

dotnet add package EmailValidator

🛠 Basic Usage

string reason;

if (EmailValidator.Core.EmailValidator.IsValid("admin@example.com", out reason))
{
    Console.WriteLine("Valid email");
}
else
{
    Console.WriteLine("Invalid: " + reason);
}

🔍 Validation Flow

The validator performs checks in this order:

1. Empty check
2. Syntax validation (RFC + IDN normalization)
3. Role-based account detection
4. DNS MX lookup
5. A-record fallback

If any check fails, validation stops immediately and returns a failure reason.

📊 Example Failure Reasons

• Email is empty
• Invalid email format
• Role-based email address
• Domain does not accept mail

⚠ Important Notes

• DNS-based validation does NOT guarantee mailbox existence.
• Some domains accept all mail (catch-all configuration).
• Port 25 SMTP probing is NOT performed.
• Validation depends on DNS availability.
• Some providers may temporarily block frequent DNS queries.

🏢 Designed For

• SaaS platforms
• Enterprise APIs
• User registration systems
• Account verification workflows
• CRM systems
• Lead validation pipelines

📦 Dependencies

• DnsClient

📝 License

MIT License