Email Address Validator

ActiveModel-style email address format validator

Whenever I have wanted to validate an email address it has been because I wanted to be somewhat certain I can send an email to someone. Usually this happens as part of a signup procedure.

At this point I have pretty much one criteria:

• Don't reject a valid email address realistically in use by a potential user. Err on the side of accepting too much.

Quite frankly, I don't care about the RFC at this point, neither does the user. I care that my users can enter their email address and get on with using my product. I appreciate it if the application catches any misspellings of their email addresses, though - this is the opportune moment for them to correct it.

Requirements

• Should not accept local email addresses: No user ever needed to sign up using "postmaster@localhost" or "bob@1.2.3.4" even though they are perfectly valid email addresses.
• Must work with I18n like Rails' built-in validators do. If not configured otherwise, the default translation key must be :invalid.

Usage examples

Simplest case

validates :email, :email_address => true

Bring your own regex

If you want to use a specific regular expression:

validates :email, :email_address => {:format => /.+@.+\..+/}

Bring your own logic

If a regular expression isn't enough for you, you can include your own rules for email addresses. For example, you could validate that all email adresses belong to the same company:

validates :email, :email_address => {
  :with => proc { |address| address.end_with?("@substancelab.com") }
}

Verify domain (still to be done - pull request, anybody?)

This also checks that the domain actually has an MX record. Note this might take a while because of DNS lookups.

validates :email, :email_address => {:mx => true}

Installation

Add this line to your application's Gemfile:

gem 'activemodel-email_address_validator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activemodel-email_address_validator

Resources

• http://stackoverflow.com/questions/201323/using-a-regular-expression-to-validate-an-email-address
• http://davidcel.is/blog/2012/09/06/stop-validating-email-addresses-with-regex/
• http://blog.myitcv.org.uk/2013/03/14/validators-in-rails-using-email-as-an-example.html

Other libraries

Serverside

• https://github.com/balexand/email_validator
• https://github.com/codyrobbins/active-model-email-validator
• https://github.com/franckverrot/activevalidators
• https://github.com/hallelujah/valid_email
• https://github.com/micke/valid_email2
• https://github.com/validates-email-format-of/validates_email_format_of

Clientside

• https://github.com/mailcheck/mailcheck

Contributing

1. Fork it ( https://github.com/substancelab/activemodel-email_address_validator/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request