EmailValidator

An email validator for Rails 3+.

Supports RFC-2822-compliant and RFC-5321-compliant email validation using RFC-3696 validation.

Formerly found at: https://github.com/balexand/email_validator

Validation philosophy

The default validation provided by this gem (the :loose configuration option) is extremely loose. It just checks that there's an @ with something before and after it without any whitespace. See this article by David Gilbertson for an explanation of why.

We understand that many use cases require an increased level of validation. This is supported by using the :strict validation mode. Additionally, the :rfc RFC-compliant mode will consider technically valid emails address as valid which may not be wanted, such as the valid user or user@somehost addresses. These would be valid in :rfc mode but not valid in :loose or :strict.

Installation

Add to your Gemfile:

gem 'email_validator'

Run:

bundle install

Usage

Add the following to your model:

validates :my_email_attribute, email: true

You may wish to allow domains without a FQDN, like user@somehost. While this is technically a valid address, it is uncommon to consider such address valid. We will consider them valid by default with the :loose checking. Disallowed by setting require_fqdn: true or by enabling :strict checking:

validates :my_email_attribute, email: {mode: :strict, require_fqdn: true}

You can also limit to a single domain (e.g: you have separate User and AdminUser models and want to ensure that AdminUser emails are on a specific domain):

validates :my_email_attribute, email: {domain: 'example.com'}

Configuration

Default configuration can be overridden by setting options in config/initializers/email_validator.rb:

if defined?(EmailValidator)
  # To completely override the defaults
  EmailValidator.default_options = {
    allow_nil: false,
    domain: nil,
    require_fqdn: nil,
    mode: :loose
  }

  # or just a few options
  EmailValidator.default_options.merge!({ domain: 'mydomain.com' })
end

Loose mode

This it the default validation mode of this gem. It is intentionally extremely loose (see the Validation Philosophy section above. It just checks that there's an @ with something before and after it without any whitespace.

Strict mode

Enabling :strict checking will check for a "normal" email format that would be expected in most common everyday usage. Strict mode basically checks for a properly sized and formatted mailbox label, a single "@" symbol, and a properly sized and formatted FQDN. Enabling :strict mode will also enable :require_fqdn configuration option.

Strict mode can be enabled globally by requiring email_validator/strict in your Gemfile, by setting the option in config/initializers/email_validator.rb, or by specifying the option in a specific validates call.

• Gemfile:

  gem 'email_validator', require: 'email_validator/strict'

• config/initializers/email_validator.rb:

  if defined?(EmailValidator)
    EmailValidator.default_options[:mode] = :strict
  end

• validates call:

  validates :my_email_attribute, email: {mode: :strict}

RFC mode

In order to have RFC-compliant validation (according to http://www.remote.org/jochen/mail/info/chars.html), enable :rfc mode.

You can do this globally by requiring email_validator/rfc in your Gemfile, by setting the options in config/initializers/email_validator.rb, or you can do this in a specific validates call.

• Gemfile:

  gem 'email_validator', require: 'email_validator/rfc'

• config/initializers/email_validator.rb:

  if defined?(EmailValidator)
    EmailValidator.default_options[:mode] = :rfc
  end

• validates call:

  validates :my_email_attribute, email: {mode: :rfc}

Validation outside a model

If you need to validate an email outside a model, you can get the regexp:

Loose/default mode

EmailValidator.valid?('[email protected]') # boolean

Requiring a FQDN

EmailValidator.valid?('narf@somehost') # boolean false
EmailValidator.invalid?('narf@somehost', require_fqdn: false) # boolean true

NB: Enabling strict mode (mode: :strict) enables require_fqdn (require_fqdn: true), overridding any require_fqdn: false while mode: :strict is set.

Requiring a specific domain

EmailValidator.valid?('[email protected]', domain: 'foo.com') # boolean false
EmailValidator.invalid?('[email protected]', domain: 'foo.com') # boolean true

Strict mode

EmailValidator.regexp(mode: :strict) # returns the regex
EmailValidator.valid?('[email protected]', mode: :strict) # boolean

RFC mode

EmailValidator.regexp(mode: :rfc) # returns the regex
EmailValidator.valid?('[email protected]', mode: :rfc) # boolean

Thread safety

This gem is thread safe, with one caveat: EmailValidator.default_options must be configured before use in a multi-threaded environment. If you configure default_options in a Rails initializer file, then you're good to go since initializers are run before worker threads are spawned.

Alternative gems

Do you prefer a different email validation gem? If so, open an issue with a brief explanation of how it differs from this gem. I'll add a link to it in this README.

• email_address (#58)
• email_verifier (#65)

Maintainers

All thanks is given to Brian Alexander (balexand) for is initial work on this gem.

Currently maintained by:

• Karl Wilbur (https://github.com/karlwilbur)
• K&R Software (https://github.com/K-and-R)