Adding options to register observers and interceptors through ActionMailer::Base.register_observer and ActionMailer::Base.register_interceptor. These hook into Mail.register_interceptor and Mail.register_observer. Also bumped Mail requirement to 2.1.3

Signed-off-by: José Valim <jose.valim@gmail.com>

actionmailer/actionmailer.gemspec

@@ -18,6 +18,6 @@ Gem::Specification.new do |s|
   s.has_rdoc = true
 
   s.add_dependency('actionpack',  '= 3.0.0.beta1')
-  s.add_dependency('mail',        '~> 2.1.2')
+  s.add_dependency('mail',        '~> 2.1.3')
   s.add_dependency('text-format', '~> 1.0.0')
 end

actionmailer/lib/action_mailer/base.rb

@@ -181,6 +181,18 @@ module ActionMailer #:nodoc:
   # and the second being a <tt>application/pdf</tt> with a Base64 encoded copy of the file.pdf book
   # with the filename +free_book.pdf+.
   #
+  # = Observing and Intercepting Mails
+  # 
+  # ActionMailer provides hooks into the Mail observer and interceptor methods.  These allow you to
+  # register objects that are called during the mail delivery life cycle.
+  # 
+  # An observer object must implement the <tt>:delivered_email(message)</tt> method which will be
+  # called once for every email sent after the email has been sent.
+  # 
+  # An interceptor object must implement the <tt>:delivering_email(message)</tt> method which will be
+  # called before the email is sent, allowing you to make modifications to the email before it hits
+  # the delivery agents.  Your object should make and needed modifications directly to the passed
+  # in Mail::Message instance.
   #
   # = Configuration options
   #
@@ -265,6 +277,9 @@ module ActionMailer #:nodoc:
 
     include ActionMailer::OldApi
     include ActionMailer::DeprecatedApi
+    
+    delegate :register_observer, :to => Mail
+    delegate :register_interceptor, :to => Mail
 
     private_class_method :new #:nodoc:
 

actionmailer/test/base_test.rb

@@ -502,6 +502,32 @@ class BaseTest < ActiveSupport::TestCase
     mail = BaseMailer.welcome_from_another_path(['unknown/invalid', 'another.path/base_mailer'])
     assert_equal("Welcome from another path", mail.body.encoded)
   end
+  
+  # Before and After hooks
+  
+  class MyObserver
+    def self.delivered_email(mail)
+    end
+  end
+  
+  test "you can register an observer to the mail object that gets informed on email delivery" do
+    ActionMailer::Base.register_observer(MyObserver)
+    mail = BaseMailer.welcome
+    MyObserver.expects(:delivered_email).with(mail)
+    mail.deliver
+  end
+
+  class MyInterceptor
+    def self.delivering_email(mail)
+    end
+  end
+
+  test "you can register an interceptor to the mail object that gets passed the mail object before delivery" do
+    ActionMailer::Base.register_interceptor(MyInterceptor)
+    mail = BaseMailer.welcome
+    MyInterceptor.expects(:delivering_email).with(mail)
+    mail.deliver
+  end
 
   protected