A simple Ruby EmailAddress class

Question

I wrote this short, plain Ruby lib to handle email address validation inside and outside of Rails applications, and I would like to know what you think.

require "i18n"
class EmailAddress
 VALID_EMAIL_ADDRESS_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
 def self.malformed?(email)
 email !~ VALID_EMAIL_ADDRESS_REGEX
 end
 def self.valid?(email)
 !malformed?(email)
 end
 attr_reader :email, :i18n_scope, :errors
 def initialize(email, i18n_scope: [:models, :email_address])
 @email = email
 @i18n_scope = i18n_scope
 @errors = []
 end
 def valid?
 validate
 errors.empty?
 end
 def validate
 message = I18n.t(:invalid, scope: i18n_scope)
 errors.push(message) if EmailAddress.malformed?(email)
 end
end

Usage can be as simple as:

if EmailAddress.valid?(params[:email))
 # do something
end

Or for remote validations, for example:

def email
 email = EmailAddress.new(params[:email])
 if email.valid?
 render nothing: true, status: 200
 else
 render json: { errors: email.errors }, status: 422
 end
end

• Devon Parsons: The absolute most reliable way to test if an email is valid or not is to check the response of isemail.info/#{emailaddress}. Unfortunately it doesn't appear that he has a ruby gem for it, so if you have an internet connection then that should be your first choice.
• Mohamad: I might write a gem for that then!

Answer 1

The Regex will validate some email addresses. Because the Domain Name System allows UniCode. the Regex does not match all valid characters in the Doman Name. Therefore it will not validate all valid email addresses.

Alternatives:

Validating over all allowable Unicode with Regex in a meaningful way is non-trivial.

1. Sending a confirmation email requiring reply is a straight-forward method for validating email procedurally.

2. When possible, not collecting email addresses at all is easy to implement.