Alos.Email.Validation 1.1.0

Alos.Email.Validation

Email validation library for anti-abuse protection in SaaS applications.

Features

• Provider-Specific Normalization - Gmail dots/plus, Outlook plus, ProtonMail plus, etc.
• Relay Service Blocking - Apple Hide My Email, Firefox Relay, DuckDuckGo, SimpleLogin, etc.
• Disposable Domain Detection - 38,000+ known disposable email providers
• MX Record Verification - DNS-based domain validation with fail-open strategy
• Custom Blocklist/Allowlist - Override built-in lists with your own domains
• Hot-Reload - Runtime blocklist updates without redeployment
• Auto-Update - Background service for periodic blocklist updates from GitHub
• Thread-Safe - All operations are safe for concurrent access

Installation

dotnet add package Alos.Email.Validation

Quick Start

// Register services
builder.Services.AddEmailValidation(builder.Configuration);

// Or with auto-update
builder.Services.AddEmailValidationWithAutoUpdate(builder.Configuration);

{
  "EmailValidation": {
    "BlocklistDirectory": "/var/lib/alos/email-blocklists",
    "EnableAutoUpdate": true,
    "UpdateInterval": "1.00:00:00",
    "InitialUpdateDelay": "00:00:30",
    "CustomBlocklist": ["spammer.com"],
    "CustomAllowlist": ["legitimate-service.com"],
    "CustomBlocklistUrls": ["https://example.com/my-blocklist.txt"],
    "CustomAllowlistUrls": ["https://example.com/my-allowlist.txt"]
  }
}

Usage

public class RegistrationService(IEmailValidationService emailValidator)
{
    public async Task<bool> RegisterAsync(string email, CancellationToken ct)
    {
        // Full async validation (includes MX check)
        var result = await emailValidator.ValidateAsync(email, ct);
        if (!result.IsValid)
        {
            // result.Error: InvalidFormat, RelayService, Disposable, InvalidDomain
            return false;
        }

        // Or use individual checks
        if (emailValidator.IsRelayService(email))
            return false; // Relay services not allowed

        if (emailValidator.IsDisposable(email))
            return false; // Disposable emails not allowed

        // Get normalized email for uniqueness checks
        var normalized = emailValidator.Normalize(email);

        // Continue with registration...
        return true;
    }
}

Components

Framework Support

• .NET 8.0
• .NET 9.0
• .NET 10.0

License

Apache-2.0 License