Validate e-mail addresses against RFC 2822 and RFC 3696.
Installing as a gem:
gem install validates_email_format_of
Installing as a Ruby on Rails 2 plugin:
./script/plugin install http://github.com/alexdunae/validates_email_format_of.git
Or in your Rails 3 Gemfile
gem 'validates_email_format_of', :git => 'git://github.com/alexdunae/validates_email_format_of.git'
class Person < ActiveRecord::Base validates_email_format_of :email end # Rails 3 class Person < ActiveRecord::Base validates :email, :email_format => {:message => 'is not looking good'} end
As of version 1.4, it’s possible to run e-mail validation tests (including MX checks) without using ActiveRecord or even touching a database.  The validate_email_format method will return nil on a valid e-mail address or an array of error messages for invalid addresses.
results = ValidatesEmailFormatOf::validate_email_format(email, options) if results.nil? # success! else puts results.join(', ') end
:message
   String. A custom error message (default is: " does not appear to be a valid e-mail address")
:on
   Symbol. Specifies when this validation is active (default is :save, other options :create, :update)
:allow_nil
   Boolean. Allow nil values (default is false)
:allow_blank
   Boolean. Allow blank values (default is false)
:check_mx
   Boolean. Check domain for a valid MX record (default is false)
:if
   Specifies a method, proc or string to call to determine if the validation should occur 
   (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, 
   proc or string should return or evaluate to a true or false value. 
:unless
   See :if option.
:local_length
  Maximum number of characters allowed in the local part (default is 64)
:domain_length
  Maximum number of characters allowed in the domain part (default is 255)
To execute the unit tests run rake test.
The unit tests for this plugin use an in-memory sqlite3 database.
Written by Alex Dunae (dunae.ca), 2006-11.
Many thanks to the plugin’s recent contributors: github.com/alexdunae/validates_email_format_of/contributors
Thanks to Francis Hwang (fhwang.net/) 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 (www.riverocktech.com/) for creating the 1.4 update.
Thanks to George Anderson (github.com/george) and ‘history’ (github.com/history) for creating the 1.4.1 update.