cartodb/config/initializers/rfc822.rb

# coding: UTF-8

module EmailAddressValidator
  module Regexp
    ATEXT = /[A-Za-z0-9!#\$%&'\*\+\-\/=\?\^_`\{\|\}\~]/
    DOT_ATOM = /(?:#{ATEXT})+(?:\.(?:#{ATEXT})+)*/

    TEXT = /[\x01-\x09\x0B\x0C\x0E-\x7F]/
    QTEXT = /[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7E]/
    QUOTED_PAIR = /\\#{TEXT}/
    QCONTENT = /(?:#{QTEXT}|#{QUOTED_PAIR})/
    QUOTED_STRING = /"(?:\s*#{QCONTENT})*\s*"/

    DTEXT = /[\x01-\x08\x0B\x0C\x0E-\x1F\x21-\x5A\x5E-\x7E]/
    DCONTENT = /(?:#{DTEXT}|#{QUOTED_PAIR})/
    DOMAIN_LITERAL = /\[(?:\s*#{DCONTENT})*\s*\]/
    DOMAIN = /(?:#{DOT_ATOM}|#{DOMAIN_LITERAL})/

    LOCAL_PART = /(?:#{DOT_ATOM}|#{QUOTED_STRING})/

    ADDR_SPEC = /^(#{LOCAL_PART})@(#{DOMAIN})$/
  end
end

# Taken from Rails examples, replacing with ADDR_SPEC
# the original regexp: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i
class EmailValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    return unless value
    if value.is_a?(Array)
      value.each { |v| validate_value(record, attribute, v) }
    else
      validate_value(record, attribute, value)
    end
  end

  private

  def validate_value(record, attribute, value)
    unless value =~ EmailAddressValidator::Regexp::ADDR_SPEC
      record.errors[attribute] << (options[:message] || "#{value} is not an email")
    end
  end
end