MailChecker is a cross-platform library for determining whether an email address is from a disposable or temporary email provider. It is implemented in 10+ languages (Node.js, PHP, Python, Ruby, Rust, Go, Java, Elixir, Clojure, etc.) via a centralized template-based code generation system. The library's core is a curated blacklist of over 55,000 disposable email domains stored in a plain text file (`list.txt`). Each platform provides a tiny API: `isValid(email)` returns `true` if the email format is valid AND its domain is not in the blacklist, and `blacklist()` to retrieve the domain list. The code generation pipeline (`lib/generator.js`) uses Mustache templates (`*.tmpl.*`) to produce optimized platform-specific code. The repository also includes domain cleanup scripts and comprehensive per-platform tests run in Docker containers. This is a purely application-oriented library; it does not contain data pipelines, ML models, or research artifacts.
Reacher is an open-source email verification system written in Rust. It checks if an email address exists without sending any email by performing syntax validation, MX record lookup, SMTP connection with intelligent response parsing, and miscellaneous checks (disposable, role-based, gravatar, haveibeenpwned). The system is structured as a Rust workspace with four crates: a core library (`check-if-email-exists`), a CLI binary, an HTTP backend server (`reacher_backend`), and an AWS SQS Lambda worker. The backend provides REST API endpoints for single and bulk email verification, supports queue-based scaling via RabbitMQ, and stores results in PostgreSQL. It features a flexible verification method configuration allowing per-provider overrides (Gmail, Hotmail, Yahoo, etc.) with SMTP, headless browser, or API methods, and supports SOCKS5 proxies with routing rules. The codebase demonstrates strong Rust craftsmanship with clean abstractions, builder patterns, comprehensive error handling, and thorough testing.
A simple yet rigorously correct .NET library for validating email addresses according to RFC 5322 and Internationalized Email standards (RFC 653x). The core is a hand-written character-by-character parser that rejects invalid syntax while supporting quoted strings, IP literals, international characters, and length constraints per the spec. It provides a static `Validate`/`TryValidate` method and a DataAnnotations `EmailAttribute` for easy integration into ASP.NET or other validation frameworks. The library is well-tested with hundreds of valid and invalid examples, including edge cases like surrogate pairs and maximum-length addresses. It targets multiple .NET frameworks (net462, net8.0, net10.0, netstandard2.0/2.1) and is distributed as a NuGet package with signed assemblies. The code is clean, well-commented, and free of external dependencies for the core validation, making it a trustworthy component for any .NET application needing email input validation.