added config option and spec

app/models/notification.rb

@@ -68,7 +68,7 @@ def deliver(should_clean = true)
         if Mailboxer.uses_emails
           email_to = r.send(Mailboxer.email_method,self)
           unless email_to.blank?
-            NotificationMailer.send_email(self,r).deliver
+            get_mailer.send_email(self,r).deliver
           end
         end
       end
@@ -77,6 +77,9 @@ def deliver(should_clean = true)
     return temp_receipts if temp_receipts.size > 1
     return temp_receipts.first
   end
+  def get_mailer
+    Mailboxer.notification_mailer || NotificationMailer
+  end
 
   #Returns the recipients of the Notification
   def recipients

lib/mailboxer.rb

@@ -15,7 +15,8 @@ module Models
   @@email_method = :mailboxer_email
   mattr_accessor :name_method
   @@name_method = :name
-
+  mattr_accessor :notification_mailer
+
    class << self
     def setup
       yield self

spec/mailboxer_spec.rb

@@ -4,4 +4,15 @@
   it "should be valid" do
     Mailboxer.should be_a(Module)
   end
-end
+
+  describe "configuring notification mailer" do
+    before { Mailboxer.notification_mailer.should eq nil }
+
+    it "can override notification mailer" do
+      Mailboxer.notification_mailer = "foo"
+      Mailboxer.notification_mailer.should eq "foo"
+    end
+
+    after { Mailboxer.notification_mailer.should eq nil }
+  end
+end

spec/models/notification_spec.rb

@@ -60,5 +60,18 @@
     notification.body.should=="Body"
 
   end
-
+
+  describe "#get_mailer obtains mailer from config" do
+    before { Mailboxer.notification_mailer.should be_nil }
+
+    it "defaults to NotificationMailer" do
+      subject.get_mailer.should eq NotificationMailer
+    end
+    it "can be overriden on Mailboxer" do
+      Mailboxer.notification_mailer = 'foo'
+      subject.get_mailer.should eq 'foo'
+    end
+
+    after { Mailboxer.notification_mailer = nil }
+  end
 end