Add OverrideRecipientSMTP delivery method

lib/mail/configuration.rb

@@ -31,6 +31,8 @@ def lookup_delivery_method(method)
         Mail::SMTP
       when :smtp
         Mail::SMTP
+      when :override_recipient_smtp
+        Mail::OverrideRecipientSMTP
       when :sendmail
         Mail::Sendmail
       when :exim

lib/mail/network.rb

@@ -2,6 +2,7 @@
 
 module Mail
   autoload :SMTP, 'mail/network/delivery_methods/smtp'
+  autoload :OverrideRecipientSMTP, 'mail/network/delivery_methods/override_recipient_smtp'
   autoload :FileDelivery, 'mail/network/delivery_methods/file_delivery'
   autoload :Sendmail, 'mail/network/delivery_methods/sendmail'
   autoload :Exim, 'mail/network/delivery_methods/exim'

lib/mail/network/delivery_methods/override_recipient_smtp.rb

@@ -0,0 +1,69 @@
+module Mail
+  # == Sending Email with Override Recipient SMTP
+  #
+  # Use the OverrideRecipientSMTP delivery method when you don't want your program
+  # to accidentally send emails to addresses other than the overridden recipient
+  # which you configure.
+  #
+  # An example use case is in your web app's staging environment, your development
+  # team will receive all staging emails without accidentally emailing users with
+  # active email addresses in the database.
+  #
+  # === Sending via OverrideRecipientSMTP
+  #
+  #   Mail.defaults do
+  #     delivery_method :override_recipient_smtp, :to => '[email protected]'
+  #   end
+  #
+  # === Sending to multiple email addresses
+  #
+  #   Mail.defaults do
+  #     delivery_method :override_recipient_smtp,
+  #       :to => ['[email protected]', '[email protected]']
+  #   end
+  #
+  # === Debug
+  #
+  # The original to, cc, and bcc fields are stored in these custom email headers
+  # for debugging:
+  #
+  #   X-Override-To
+  #   X-Override-Cc
+  #   X-Override-Bcc
+  #
+  class OverrideRecipientSMTP < Mail::SMTP
+    def initialize(values)
+      unless values[:to]
+        raise ArgumentError.new('A :to option is required when using :override_recipient_smtp')
+      end
+
+      super(values)
+    end
+
+    def deliver!(mail)
+      store_in_custom_headers(mail)
+
+      mail.to = settings[:to]
+      mail.cc = nil
+      mail.bcc = nil
+
+      super(mail)
+    end
+
+    private
+
+    def store_in_custom_headers(mail)
+      {
+        'X-Override-To' => mail.to,
+        'X-Override-Cc' => mail.cc,
+        'X-Override-Bcc' => mail.bcc
+      }.each do |header, addresses|
+        if addresses
+          addresses.each do |address|
+            mail.header = "#{mail.header}\n#{header}: #{address}"
+          end
+        end
+      end
+    end
+  end
+end

spec/mail/network/delivery_methods/override_recipient_smtp_spec.rb

@@ -0,0 +1,49 @@
+# encoding: utf-8
+require 'spec_helper'
+
+describe 'override recipient SMTP delivery method' do
+  it 'raises an error when :to option is missing' do
+    doing do
+      Mail.defaults do
+        delivery_method :override_recipient_smtp
+      end
+    end.should raise_error(ArgumentError)
+  end
+
+  it 'supresses email delivery to, cc, and bcc fields' do
+    Mail.defaults do
+      delivery_method :override_recipient_smtp, :to => '[email protected]'
+    end
+
+    mail = Mail.deliver do
+      from '[email protected]'
+      to   '[email protected]'
+      cc   '[email protected]'
+      bcc  '[email protected]'
+    end
+
+    response = mail.deliver!
+
+    response.to.should eq ['[email protected]']
+    response.cc.should eq []
+    response.bcc.should eq []
+    response.header['X-Override-To'].to_s.should eq '[[email protected], [email protected]]'
+    response.header['X-Override-Cc'].to_s.should eq '[email protected]'
+    response.header['X-Override-Bcc'].to_s.should eq '[email protected]'
+  end
+
+  it 'can accept an array as configuration' do
+    Mail.defaults do
+      delivery_method :override_recipient_smtp,
+        :to => ['[email protected]', '[email protected]']
+    end
+
+    mail = Mail.deliver do
+      from '[email protected]'
+    end
+
+    response = mail.deliver!
+
+    response.to.should eq ['[email protected]', '[email protected]']
+  end
+end