mailer.setup

script/generate mailer mailer

config/environments/development.rb
ActionMailer::Base.delivery_method = :sendmail 
ActionMailer::Base.sendmail_settings = {  
  :location => '/usr/sbin/sendmail',  
  :arguments => '-i -t' } 
ActionMailer::Base.perform_deliveries = true 
ActionMailer::Base.raise_delivery_errors = true 
ActionMailer::Base.default_charset = "iso-8859-1"

config/environments/production.rb
ActionMailer::Base.smtp_settings = {  
  :address => "smtp.gmail.com",  
  :port => 587,  
  :domain => "domain.com",  
  :user_name => "[email protected]",  
  :password => "password",  
  :authentication => :plain 
} 

config/environment.rb
ActionMailer::Base.register_template_extension('haml')