I had some trouble with this as well, but this came in handy:
http://wiki.dreamhost.com/ActionMailer
This is what mine looks like, but it is specific for sending emails from a subdomain:
# Include your application configuration below ActionMailer::Base.server_settings = { :address => "mail.domain.com", :port => 25, :domain => 'subdomain.domain.com', :user_name => "m1234567", :password => "password", :authentication => :login }
