Create a file named as setup_mail.rb in config/initializers/ folder so that it looks like
config/initializers/setup_mail.rb
and put the below code in that file:-
ActionMailer::Base.smtp_settings = {
:address => "smtp.gmail.com",
:port => 587,
:domain => 'www.yourdomain.com',
:user_name => "myaddress@gmail.com",
:password => "mypassword",
:authentication => 'plain',
:enable_starttls_auto => true
}
ActionMailer::Base.default_url_options[:host] = "www.yourdomain.com"