Email Validator

⚠️ Alpha Release - Work in Progress

A RFC-compliant email validation library for Common Lisp.

Features

• RFC 5321 compliant email validation
• Validates local part (before @) and domain part (after @)
• Supports special characters allowed by RFC
• Supports IP literals (IPv4 and IPv6)
• Enforces proper length limits:
  • Local part: max 64 characters
  • Domain labels: max 63 characters
  • Total email: max 320 characters
• ASCII-only validation (no Unicode)
• Zero dependencies

Installation

This library uses ASDF for system definition.

Option 1: Manual Installation

1. Clone to a location where ASDF can find it:

   cd ~/common-lisp/  # or ~/quicklisp/local-projects/
   git clone <repository-url> email-validator

2. Load the system:

   (asdf:load-system :email-validator)

Option 2: Quicklisp (if published)

(ql:quickload :email-validator)

Usage

;; Load the system
(asdf:load-system :email-validator)

;; Validate email addresses
(email-validator:email-p "[email protected]") ; => T

(email-validator:email-p "invalid.email")    ; => NIL
(email-validator:email-p "@invalid.com")     ; => NIL
(email-validator:email-p "user@")            ; => NIL

;; Advanced examples
(email-validator:email-p "[email protected]")  ; => T
(email-validator:email-p "user@[192.168.1.1]")    ; => T
(email-validator:email-p "user@[IPv6:2001:db8::1]") ; => T

API

Functions

• (email-p email) → boolean

Returns T if the email is valid according to RFC specifications, NIL otherwise.

Validation Rules

Local Part (before @)

• Max 64 characters
• Allowed characters: alphanumeric + . ! # $ % & ' * + - / = ? ^ _ { | } ~`
• Cannot start or end with a dot
• No consecutive dots
• ASCII only

Domain Part (after @)

• Domain names: standard DNS rules
• IP literals: [192.168.1.1] or [IPv6:2001:db8::1]
• Labels max 63 characters each
• Must have at least 2 labels (e.g., example.com)
• ASCII only

Overall

• Single @ symbol required
• Max 320 characters total
• Must be a string

Running Tests

;; Run all tests
(asdf:test-system :email-validator)

;; Or load and run directly
(asdf:load-system :email-validator/tests)
(email-validator.tests:run-tests)

The test suite includes 43 comprehensive tests covering valid emails, invalid emails, edge cases, and RFC compliance.

Examples

See example.lisp for interactive examples and usage patterns.

Goals

• Support for quoted strings in local parts (RFC 5321)
• Email address comments parsing
• Internationalized domain names (IDN) support
• Unicode/non-ASCII character validation
• Advanced RFC format compatibility
• Performance optimizations
• Extended API with detailed validation results
• Batch validation support
• Configurable validation strictness levels

Contributing

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass: (asdf:test-system :email-validator)
5. Submit a pull request

License

MIT License - see LICENSE file for details.

Author

Created by mtha790