ActionMailer server_settings

ActionMailer::Base.server_settings = {
   :address => "mail.mydomain.com",
   :port => 25,
   :user_name => foo,
   :password => "password",
   :authentication => :cram_md5
 }
 ActionMailer::Base.default_charset = "iso-2022-jp"
 ActionMailer::Base.encode_subject = false

:authentication には，:plain, :login, :cram_md5 を指定できる。