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Validate e-mail addreses against RFC 2822 and RFC 3696 with this Ruby on Rails plugin and gem.


validates_email_format_of Gem and Rails Plugin

Validate e-mail addresses against RFC 2822 and RFC 3696.


Installing as a gem:

gem install validates_email_format_of

Or in your Gemfile:

gem 'validates_email_format_of'


# Rails
# I18n locales are loaded automatically.
class Person < ActiveRecord::Base
  validates_email_format_of :email, :message => 'is not looking good'
  # OR
  validates :email, :email_format => { :message => 'is not looking good' }

# Now you can test your model using RSpec:
require "validates_email_format_of/rspec_matcher"
describe Person do
  it { should validate_email_format_of(:email).with_message('is not looking good') }

# If you're not using Rails (which really means, if you're not using ActiveModel::Validations)
ValidatesEmailFormatOf::load_i18n_locales # Optional, if you want error messages to be in your language
I18n.locale = :pl # If, for example, you want Polish error messages.
ValidatesEmailFormatOf::validate_email_format("") # => nil
ValidatesEmailFormatOf::validate_email_format("invalid_because_there_is_no_at_symbol") # => ["does not appear to be a valid e-mail address"]


   String. A custom error message when the email format is invalid (default is: "does not appear to be a valid e-mail address")
   Boolean. Check domain for a valid MX record (default is false)
   String. A custom error message when the domain does not match a valid MX record (default is: "is not routable").  Ignored unless :check_mx option is true.
  Maximum number of characters allowed in the local part (everything before the '@') (default is 64)
  Maximum number of characters allowed in the domain part (everything after the '@') (default is 255)
  Boolean. Return the I18n key of the error message instead of the error message itself (default is false)
  Specify a custom Regex as the valid email format.
:on, :if, :unless, :allow_nil, :allow_blank, :strict
   Standard ActiveModel validation options.  These work in the ActiveModel/ActiveRecord/Rails syntax only.
   See for details.


To execute the unit tests run rspec.

Tested in Ruby 1.8.7, 1.9.2, 1.9.3, 2.0.0, 2.1.2, JRuby and REE 1.8.7.


If you think we're letting some rules about valid email formats slip through the cracks, don't just update the Regex. Instead, add a failing test, and demonstrate that the described email address should be treated differently. A link to an appropriate RFC is the best way to do this. Then change the gem code to make the test pass.

describe "" do
  # According to http://..., this email address IS NOT valid.
  it { should have_errors_on_email.because("does not appear to be valid") }
describe "" do
  # According to http://..., this email address IS valid.
  it { should_not have_errors_on_email }

Yes, our Rspec syntax is that simple!



Written by Alex Dunae (, 2006-11.

Many thanks to the plugin's recent contributors:

Thanks to Francis Hwang ( at Diversion Media for creating the 1.1 update.

Thanks to Travis Sinnott for creating the 1.3 update.

Thanks to Denis Ahearn at Riverock Technologies ( for creating the 1.4 update.

Thanks to George Anderson ( and 'history' ( for creating the 1.4.1 update.

Thanks to Isaac Betesh ( for converting tests to Rspec and refactoring for version 1.6.0.

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