Merge pull request #16582 from cristianbica/actionmailer-deprecate-deliver

Deprecated ActionMailer .deliver and updated ActionMailer / ActiveJob docs/guide

19 files changed, 227 insertions, 101 deletions

diff --git a/actionmailer/CHANGELOG.md b/actionmailer/CHANGELOG.md
index a4923de045..1ff4db41a3 100644
--- a/actionmailer/CHANGELOG.md
+++ b/actionmailer/CHANGELOG.md
@@ -1,7 +1,9 @@
-*   Added #deliver_later in addition to #deliver, which will enqueue a job to render and
-    deliver the mail instead of delivering it right at that moment. The job is enqueued 
-    using the new Active Job framework in Rails, and will use whatever queue is configured for Rails.
-    
+*   Added #deliver_later, #deliver_now and deprecate #deliver in favour of
+    #deliver_now. #deliver_later will enqueue a job to render and deliver
+    the mail instead of delivering it right at that moment. The job is enqueued
+    using the new Active Job framework in Rails, and will use whatever queue is
+    configured for Rails.
+
     *DHH/Abdelkader Boudih/Cristian Bica*
 
 *   Make ActionMailer::Previews methods class methods. Previously they were
diff --git a/actionmailer/README.rdoc b/actionmailer/README.rdoc
index ceca912ada..3b8e3ed749 100644
--- a/actionmailer/README.rdoc
+++ b/actionmailer/README.rdoc
@@ -65,12 +65,12 @@ In order to send mails, you simply call the method and then call +deliver+ on th
 
 Calling the method returns a Mail Message object:
 
-  message = Notifier.welcome("david@loudthinking.com")  # => Returns a Mail::Message object
-  message.deliver                                       # => delivers the email
+  message = Notifier.welcome("david@loudthinking.com")   # => Returns a Mail::Message object
+  message.deliver_now                                    # => delivers the email
 
 Or you can just chain the methods together like:
 
-  Notifier.welcome("david@loudthinking.com").deliver    # Creates the email and sends it immediately
+  Notifier.welcome("david@loudthinking.com").deliver_now # Creates the email and sends it immediately
 
 == Setting defaults
 
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 9aae14ec8c..fc2d0936f9 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -138,9 +138,20 @@ module ActionMailer
   # Once a mailer action and template are defined, you can deliver your message or create it and save it
   # for delivery later:
   #
-  #   Notifier.welcome(david).deliver # sends the email
-  #   mail = Notifier.welcome(david)  # => a Mail::Message object
-  #   mail.deliver                    # sends the email
+  #   Notifier.welcome(david).deliver_now # sends the email
+  #   mail = Notifier.welcome(david)      # => an ActionMailer::MessageDeliver object
+  #   mail.deliver_now                    # sends the email
+  #
+  # The <tt>ActionMailer::MessageDeliver</tt> class is a wrapper around a <tt>Mail::Message</tt> object. If
+  # you want direct access to the <tt>Mail::Message</tt> object you can call the <tt>message</tt> method on
+  # the <tt>ActionMailer::MessageDeliver</tt> object.
+  #
+  #   Notifier.welcome(david).message     # => a Mail::Message object
+  #
+  # ActionMailer is nicely integrated with ActiveJob so you can send emails in the background (example: outside
+  # of the request-response cycle, so the user doesn't have to wait on it):
+  #
+  #   Notifier.welcome(david).deliver_later # enqueue the email sending to ActiveJob
   #
   # You never instantiate your mailer class. Rather, you just call the method you defined on the class itself.
   #
@@ -322,8 +333,8 @@ module ActionMailer
   #   end
   #
   # Methods must return a <tt>Mail::Message</tt> object which can be generated by calling the mailer
-  # method without the additional <tt>deliver</tt>. The location of the mailer previews
-  # directory can be configured using the <tt>preview_path</tt> option which has a default
+  # method without the additional <tt>deliver_now</tt> / <tt>deliver_later</tt>. The location of the
+  # mailer previews directory can be configured using the <tt>preview_path</tt> option which has a default
   # of <tt>test/mailers/previews</tt>:
   #
   #   config.action_mailer.preview_path = "#{Rails.root}/lib/mailer_previews"
diff --git a/actionmailer/lib/action_mailer/delivery_job.rb b/actionmailer/lib/action_mailer/delivery_job.rb
index b2cfa245fd..622f202695 100644
--- a/actionmailer/lib/action_mailer/delivery_job.rb
+++ b/actionmailer/lib/action_mailer/delivery_job.rb
@@ -1,10 +1,10 @@
 require 'active_job'
 
 module ActionMailer
-  class DeliveryJob < ActiveJob::Base
+  class DeliveryJob < ActiveJob::Base #:nodoc:
     queue_as :mailers
 
-    def perform(mailer, mail_method, delivery_method, *args)
+    def perform(mailer, mail_method, delivery_method, *args) #:nodoc#
       mailer.constantize.public_send(mail_method, *args).send(delivery_method)
     end
   end
diff --git a/actionmailer/lib/action_mailer/message_delivery.rb b/actionmailer/lib/action_mailer/message_delivery.rb
index 80a0517bff..e65e79e741 100644
--- a/actionmailer/lib/action_mailer/message_delivery.rb
+++ b/actionmailer/lib/action_mailer/message_delivery.rb
@@ -1,45 +1,112 @@
 require 'delegate'
 
 module ActionMailer
+
+  # The ActionMailer::MessageDeliver class is used by ActionMailer::Base when
+  # creating a new mailer. MessageDeliver is a wrapper (Delegator subclass)
+  # around a lazy created Mail::Message. You can get direct access to the
+  # Mail::Message, deliver the email or schedule the email to be sent through ActiveJob.
+  #
+  #   Notifier.welcome(david)               # an ActionMailer::MessageDeliver object
+  #   Notifier.welcome(david).deliver_now   # sends the email
+  #   Notifier.welcome(david).deliver_later # enqueue the deliver email job to ActiveJob
+  #   Notifier.welcome(david).message       # a Mail::Message object
   class MessageDelivery < Delegator
-    def initialize(mailer, mail_method, *args)
+    def initialize(mailer, mail_method, *args) #:nodoc:
       @mailer = mailer
       @mail_method = mail_method
       @args = args
     end
 
-    def __getobj__
+    def __getobj__ #:nodoc:
       @obj ||= @mailer.send(:new, @mail_method, *@args).message
     end
 
-    def __setobj__(obj)
+    def __setobj__(obj) #:nodoc:
       @obj = obj
     end
 
-    def message #:nodoc:
+    # Returns the Mail::Message object
+    def message
       __getobj__
     end
 
+    # Enqueues the message to be delivered through ActiveJob. When the
+    # ActiveJob job runs it will send the email using #deliver_now!. That
+    # means that the message will be sent bypassing checking perform_deliveries
+    # and raise_delivery_errors, so use with caution.
+    #
+    # ==== Examples
+    #
+    #   Notifier.welcome(david).deliver_later
+    #   Notifier.welcome(david).deliver_later(in: 1.hour)
+    #   Notifier.welcome(david).deliver_later(at: 10.hours.from_now)
+    #
+    # ==== Options
+    # * <tt>in</tt>  - Enqueue the message to be delivered with a delay
+    # * <tt>at</tt>  - Enqueue the message to be delivered at (after) a specific date / time
     def deliver_later!(options={})
-      enqueue_delivery :deliver!, options
+      enqueue_delivery :deliver_now!, options
     end
 
+    # Enqueues the message to be delivered through ActiveJob. When the
+    # ActiveJob job runs it will send the email using #deliver_now.
+    #
+    # ==== Examples
+    #
+    #   Notifier.welcome(david).deliver_later
+    #   Notifier.welcome(david).deliver_later(in: 1.hour)
+    #   Notifier.welcome(david).deliver_later(at: 10.hours.from_now)
+    #
+    # ==== Options
+    # * <tt>in</tt>  - Enqueue the message to be delivered with a delay
+    # * <tt>at</tt>  - Enqueue the message to be delivered at (after) a specific date / time
     def deliver_later(options={})
-      enqueue_delivery :deliver, options
+      enqueue_delivery :deliver_now, options
+    end
+
+    # Delivers a message. The message will be sent bypassing checking perform_deliveries
+    # and raise_delivery_errors, so use with caution.
+    #
+    #   Notifier.welcome(david).deliver_now!
+    #
+    def deliver_now!
+      message.deliver!
+    end
+
+    # Delivers a message:
+    #
+    #   Notifier.welcome(david).deliver_now
+    #
+    def deliver_now
+      message.deliver
+    end
+
+    def deliver! #:nodoc:
+      ActiveSupport::Deprecation.warn "#deliver! is deprecated and will be removed in Rails 5. " \
+        "Use #deliver_now! to deliver immediately or #deliver_later! to deliver through ActiveJob."
+      deliver_now!
+    end
+
+    def deliver #:nodoc:
+      ActiveSupport::Deprecation.warn "#deliver is deprecated and will be removed in Rails 5. " \
+        "Use #deliver_now to deliver immediately or #deliver_later to deliver through ActiveJob."
+      deliver_now
     end
 
     private
-    def enqueue_delivery(delivery_method, options={})
-      args = @mailer.name, @mail_method.to_s, delivery_method.to_s, *@args
-      enqueue_method = :enqueue
-      if options[:at]
-        enqueue_method = :enqueue_at
-        args.unshift options[:at]
-      elsif options[:in]
-        enqueue_method = :enqueue_in
-        args.unshift options[:in]
+
+      def enqueue_delivery(delivery_method, options={})
+        args = @mailer.name, @mail_method.to_s, delivery_method.to_s, *@args
+        enqueue_method = :enqueue
+        if options[:at]
+          enqueue_method = :enqueue_at
+          args.unshift options[:at]
+        elsif options[:in]
+          enqueue_method = :enqueue_in
+          args.unshift options[:in]
+        end
+        ActionMailer::DeliveryJob.send enqueue_method, *args
       end
-      ActionMailer::DeliveryJob.send enqueue_method, *args
-    end
   end
 end
diff --git a/actionmailer/lib/action_mailer/test_helper.rb b/actionmailer/lib/action_mailer/test_helper.rb
index 06da0dd27e..6ddacf7b79 100644
--- a/actionmailer/lib/action_mailer/test_helper.rb
+++ b/actionmailer/lib/action_mailer/test_helper.rb
@@ -6,9 +6,9 @@ module ActionMailer
     #
     #   def test_emails
     #     assert_emails 0
-    #     ContactMailer.welcome.deliver
+    #     ContactMailer.welcome.deliver_now
     #     assert_emails 1
-    #     ContactMailer.welcome.deliver
+    #     ContactMailer.welcome.deliver_now
     #     assert_emails 2
     #   end
     #
@@ -17,12 +17,12 @@ module ActionMailer
     #
     #   def test_emails_again
     #     assert_emails 1 do
-    #       ContactMailer.welcome.deliver
+    #       ContactMailer.welcome.deliver_now
     #     end
     #
     #     assert_emails 2 do
-    #       ContactMailer.welcome.deliver
-    #       ContactMailer.welcome.deliver
+    #       ContactMailer.welcome.deliver_now
+    #       ContactMailer.welcome.deliver_now
     #     end
     #   end
     def assert_emails(number)
@@ -40,7 +40,7 @@ module ActionMailer
     #
     #   def test_emails
     #     assert_no_emails
-    #     ContactMailer.welcome.deliver
+    #     ContactMailer.welcome.deliver_now
     #     assert_emails 1
     #   end
     #
diff --git a/actionmailer/test/assert_select_email_test.rb b/actionmailer/test/assert_select_email_test.rb
index 57ae3436e1..cae2e20abd 100644
--- a/actionmailer/test/assert_select_email_test.rb
+++ b/actionmailer/test/assert_select_email_test.rb
@@ -26,7 +26,7 @@ class AssertSelectEmailTest < ActionMailer::TestCase
       assert_select_email {}
     end
 
-    AssertSelectMailer.test("<div><p>foo</p><p>bar</p></div>").deliver
+    AssertSelectMailer.test("<div><p>foo</p><p>bar</p></div>").deliver_now
     assert_select_email do
       assert_select "div:root" do
         assert_select "p:first-child", "foo"
@@ -36,7 +36,7 @@ class AssertSelectEmailTest < ActionMailer::TestCase
   end
 
   def test_assert_select_email_multipart
-    AssertMultipartSelectMailer.test(html: "<div><p>foo</p><p>bar</p></div>", text: 'foo bar').deliver
+    AssertMultipartSelectMailer.test(html: "<div><p>foo</p><p>bar</p></div>", text: 'foo bar').deliver_now
     assert_select_email do
       assert_select "div:root" do
         assert_select "p:first-child", "foo"
diff --git a/actionmailer/test/base_test.rb b/actionmailer/test/base_test.rb
index fc24639bf4..d00f5aea47 100644
--- a/actionmailer/test/base_test.rb
+++ b/actionmailer/test/base_test.rb
@@ -466,12 +466,12 @@ class BaseTest < ActiveSupport::TestCase
 
   test "calling deliver on the action should deliver the mail object" do
     BaseMailer.expects(:deliver_mail).once
-    mail = BaseMailer.welcome.deliver
+    mail = BaseMailer.welcome.deliver_now
     assert_equal 'The first email on new API!', mail.subject
   end
 
   test "calling deliver on the action should increment the deliveries collection if using the test mailer" do
-    BaseMailer.welcome.deliver
+    BaseMailer.welcome.deliver_now
     assert_equal(1, BaseMailer.deliveries.length)
   end
 
@@ -484,35 +484,35 @@ class BaseTest < ActiveSupport::TestCase
 
   # Rendering
   test "you can specify a different template for implicit render" do
-    mail = BaseMailer.implicit_different_template('implicit_multipart').deliver
+    mail = BaseMailer.implicit_different_template('implicit_multipart').deliver_now
     assert_equal("HTML Implicit Multipart", mail.html_part.body.decoded)
     assert_equal("TEXT Implicit Multipart", mail.text_part.body.decoded)
   end
 
   test "should raise if missing template in implicit render" do
     assert_raises ActionView::MissingTemplate do
-      BaseMailer.implicit_different_template('missing_template').deliver
+      BaseMailer.implicit_different_template('missing_template').deliver_now
     end
     assert_equal(0, BaseMailer.deliveries.length)
   end
 
   test "you can specify a different template for explicit render" do
-    mail = BaseMailer.explicit_different_template('explicit_multipart_templates').deliver
+    mail = BaseMailer.explicit_different_template('explicit_multipart_templates').deliver_now
     assert_equal("HTML Explicit Multipart Templates", mail.html_part.body.decoded)
     assert_equal("TEXT Explicit Multipart Templates", mail.text_part.body.decoded)
   end
 
   test "you can specify a different layout" do
-    mail = BaseMailer.different_layout('different_layout').deliver
+    mail = BaseMailer.different_layout('different_layout').deliver_now
     assert_equal("HTML -- HTML", mail.html_part.body.decoded)
     assert_equal("PLAIN -- PLAIN", mail.text_part.body.decoded)
   end
 
   test "you can specify the template path for implicit lookup" do
-    mail = BaseMailer.welcome_from_another_path('another.path/base_mailer').deliver
+    mail = BaseMailer.welcome_from_another_path('another.path/base_mailer').deliver_now
     assert_equal("Welcome from another path", mail.body.encoded)
 
-    mail = BaseMailer.welcome_from_another_path(['unknown/invalid', 'another.path/base_mailer']).deliver
+    mail = BaseMailer.welcome_from_another_path(['unknown/invalid', 'another.path/base_mailer']).deliver_now
     assert_equal("Welcome from another path", mail.body.encoded)
   end
 
@@ -542,13 +542,13 @@ class BaseTest < ActiveSupport::TestCase
   test 'the view is not rendered when mail was never called' do
     mail = BaseMailer.without_mail_call
     assert_equal('', mail.body.to_s.strip)
-    mail.deliver
+    mail.deliver_now
   end
 
   test 'the return value of mailer methods is not relevant' do
     mail = BaseMailer.with_nil_as_return_value
     assert_equal('Welcome', mail.body.to_s.strip)
-    mail.deliver
+    mail.deliver_now
   end
 
   # Before and After hooks
@@ -568,7 +568,7 @@ class BaseTest < ActiveSupport::TestCase
       ActionMailer::Base.register_observer(MyObserver)
       mail = BaseMailer.welcome
       MyObserver.expects(:delivered_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -577,7 +577,7 @@ class BaseTest < ActiveSupport::TestCase
       ActionMailer::Base.register_observer("BaseTest::MyObserver")
       mail = BaseMailer.welcome
       MyObserver.expects(:delivered_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -586,7 +586,7 @@ class BaseTest < ActiveSupport::TestCase
       ActionMailer::Base.register_observer(:"base_test/my_observer")
       mail = BaseMailer.welcome
       MyObserver.expects(:delivered_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -596,7 +596,7 @@ class BaseTest < ActiveSupport::TestCase
       mail = BaseMailer.welcome
       MyObserver.expects(:delivered_email).with(mail)
       MySecondObserver.expects(:delivered_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -615,7 +615,7 @@ class BaseTest < ActiveSupport::TestCase
       ActionMailer::Base.register_interceptor(MyInterceptor)
       mail = BaseMailer.welcome
       MyInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -624,7 +624,7 @@ class BaseTest < ActiveSupport::TestCase
       ActionMailer::Base.register_interceptor("BaseTest::MyInterceptor")
       mail = BaseMailer.welcome
       MyInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -633,7 +633,7 @@ class BaseTest < ActiveSupport::TestCase
       ActionMailer::Base.register_interceptor(:"base_test/my_interceptor")
       mail = BaseMailer.welcome
       MyInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
@@ -643,7 +643,7 @@ class BaseTest < ActiveSupport::TestCase
       mail = BaseMailer.welcome
       MyInterceptor.expects(:delivering_email).with(mail)
       MySecondInterceptor.expects(:delivering_email).with(mail)
-      mail.deliver
+      mail.deliver_now
     end
   end
 
diff --git a/actionmailer/test/delivery_methods_test.rb b/actionmailer/test/delivery_methods_test.rb
index a76ac6d295..2e4e019bf7 100644
--- a/actionmailer/test/delivery_methods_test.rb
+++ b/actionmailer/test/delivery_methods_test.rb
@@ -104,21 +104,21 @@ class MailDeliveryTest < ActiveSupport::TestCase
 
   test "ActionMailer should be told when Mail gets delivered" do
     DeliveryMailer.expects(:deliver_mail).once
-    DeliveryMailer.welcome.deliver
+    DeliveryMailer.welcome.deliver_now
   end
 
   test "delivery method can be customized per instance" do
     Mail::SMTP.any_instance.expects(:deliver!)
-    email = DeliveryMailer.welcome.deliver
+    email = DeliveryMailer.welcome.deliver_now
     assert_instance_of Mail::SMTP, email.delivery_method
-    email = DeliveryMailer.welcome(delivery_method: :test).deliver
+    email = DeliveryMailer.welcome(delivery_method: :test).deliver_now
     assert_instance_of Mail::TestMailer, email.delivery_method
   end
 
   test "delivery method can be customized in subclasses not changing the parent" do
     DeliveryMailer.delivery_method = :test
     assert_equal :smtp, ActionMailer::Base.delivery_method
-    email = DeliveryMailer.welcome.deliver
+    email = DeliveryMailer.welcome.deliver_now
     assert_instance_of Mail::TestMailer, email.delivery_method
   end
 
@@ -162,14 +162,14 @@ class MailDeliveryTest < ActiveSupport::TestCase
   test "non registered delivery methods raises errors" do
     DeliveryMailer.delivery_method = :unknown
     assert_raise RuntimeError do
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
     end
   end
 
   test "undefined delivery methods raises errors" do
     DeliveryMailer.delivery_method = nil
     assert_raise RuntimeError do
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
     end
   end
 
@@ -178,7 +178,7 @@ class MailDeliveryTest < ActiveSupport::TestCase
     begin
       DeliveryMailer.perform_deliveries = false
       Mail::Message.any_instance.expects(:deliver!).never
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
     ensure
       DeliveryMailer.perform_deliveries = old_perform_deliveries
     end
@@ -188,7 +188,7 @@ class MailDeliveryTest < ActiveSupport::TestCase
     old_perform_deliveries = DeliveryMailer.perform_deliveries
     begin
       DeliveryMailer.perform_deliveries = false
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
       assert_equal [], DeliveryMailer.deliveries
     ensure
       DeliveryMailer.perform_deliveries = old_perform_deliveries
@@ -198,14 +198,14 @@ class MailDeliveryTest < ActiveSupport::TestCase
   test "raise errors on bogus deliveries" do
     DeliveryMailer.delivery_method = BogusDelivery
     assert_raise RuntimeError do
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
     end
   end
 
   test "does not increment the deliveries collection on error" do
     DeliveryMailer.delivery_method = BogusDelivery
     assert_raise RuntimeError do
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
     end
     assert_equal [], DeliveryMailer.deliveries
   end
@@ -216,7 +216,7 @@ class MailDeliveryTest < ActiveSupport::TestCase
       DeliveryMailer.delivery_method = BogusDelivery
       DeliveryMailer.raise_delivery_errors = false
       assert_nothing_raised do
-        DeliveryMailer.welcome.deliver
+        DeliveryMailer.welcome.deliver_now
       end
     ensure
       DeliveryMailer.raise_delivery_errors = old_raise_delivery_errors
@@ -228,7 +228,7 @@ class MailDeliveryTest < ActiveSupport::TestCase
     begin
       DeliveryMailer.delivery_method = BogusDelivery
       DeliveryMailer.raise_delivery_errors = false
-      DeliveryMailer.welcome.deliver
+      DeliveryMailer.welcome.deliver_now
       assert_equal [], DeliveryMailer.deliveries
     ensure
       DeliveryMailer.raise_delivery_errors = old_raise_delivery_errors
diff --git a/actionmailer/test/i18n_with_controller_test.rb b/actionmailer/test/i18n_with_controller_test.rb
index ee36b89dd6..010e44d045 100644
--- a/actionmailer/test/i18n_with_controller_test.rb
+++ b/actionmailer/test/i18n_with_controller_test.rb
@@ -17,7 +17,7 @@ end
 
 class TestController < ActionController::Base
   def send_mail
-    email = I18nTestMailer.mail_with_i18n_subject("test@localhost").deliver
+    email = I18nTestMailer.mail_with_i18n_subject("test@localhost").deliver_now
     render text: "Mail sent - Subject: #{email.subject}"
   end
 end
diff --git a/actionmailer/test/log_subscriber_test.rb b/actionmailer/test/log_subscriber_test.rb
index e7a73d6c8e..3871b16840 100644
--- a/actionmailer/test/log_subscriber_test.rb
+++ b/actionmailer/test/log_subscriber_test.rb
@@ -22,7 +22,7 @@ class AMLogSubscriberTest < ActionMailer::TestCase
   end
 
   def test_deliver_is_notified
-    BaseMailer.welcome.deliver
+    BaseMailer.welcome.deliver_now
     wait
 
     assert_equal(1, @logger.logged(:info).size)
diff --git a/actionmailer/test/message_delivery_test.rb b/actionmailer/test/message_delivery_test.rb
index 1c7406b520..49b63d7675 100644
--- a/actionmailer/test/message_delivery_test.rb
+++ b/actionmailer/test/message_delivery_test.rb
@@ -37,6 +37,17 @@ class MessageDeliveryTest < ActiveSupport::TestCase
     assert_respond_to @mail, :deliver!
   end
 
+  test '.deliver is deprecated' do
+    assert_deprecated do
+      @mail.deliver
+    end
+  end
+  test '.deliver! is deprecated' do
+    assert_deprecated do
+      @mail.deliver!
+    end
+  end
+
   test 'should respond to .deliver_later' do
     assert_respond_to @mail, :deliver_later
   end
@@ -45,7 +56,15 @@ class MessageDeliveryTest < ActiveSupport::TestCase
     assert_respond_to @mail, :deliver_later!
   end
 
-  def test_should_enqueue_and_run_correctly_in_activejob
+  test 'should respond to .deliver_now' do
+    assert_respond_to @mail, :deliver_now
+  end
+
+  test 'should respond to .deliver_now!' do
+    assert_respond_to @mail, :deliver_now!
+  end
+
+  test 'should enqueue and run correctly in activejob' do
     @mail.deliver_later!
     assert_equal 1, ActionMailer::Base.deliveries.size
   ensure
@@ -56,21 +75,21 @@ class MessageDeliveryTest < ActiveSupport::TestCase
     ret = ActionMailer::DeliveryJob.stub :enqueue, ->(*args){ args } do
       @mail.deliver_later
     end
-    assert_equal ['DelayedMailer', 'test_message', 'deliver', 1, 2, 3], ret
+    assert_equal ['DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], ret
   end
 
   test 'should enqueue the email with :deliver! delivery method' do
     ret = ActionMailer::DeliveryJob.stub :enqueue, ->(*args){ args } do
       @mail.deliver_later!
     end
-    assert_equal ['DelayedMailer', 'test_message', 'deliver!', 1, 2, 3], ret
+    assert_equal ['DelayedMailer', 'test_message', 'deliver_now!', 1, 2, 3], ret
   end
 
   test 'should enqueue a delivery with a delay' do
     ret = ActionMailer::DeliveryJob.stub :enqueue_in, ->(*args){ args } do
       @mail.deliver_later in: 600
     end
-    assert_equal [600, 'DelayedMailer', 'test_message', 'deliver', 1, 2, 3], ret
+    assert_equal [600, 'DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], ret
   end
 
   test 'should enqueue a delivery at a specific time' do
@@ -78,7 +97,7 @@ class MessageDeliveryTest < ActiveSupport::TestCase
     ret = ActionMailer::DeliveryJob.stub :enqueue_at, ->(*args){ args } do
       @mail.deliver_later at: later_time
     end
-    assert_equal [later_time, 'DelayedMailer', 'test_message', 'deliver', 1, 2, 3], ret
+    assert_equal [later_time, 'DelayedMailer', 'test_message', 'deliver_now', 1, 2, 3], ret
   end
 
 end
diff --git a/actionmailer/test/test_helper_test.rb b/actionmailer/test/test_helper_test.rb
index 1ff08a3b6e..96b75ff2e0 100644
--- a/actionmailer/test/test_helper_test.rb
+++ b/actionmailer/test/test_helper_test.rb
@@ -48,7 +48,7 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_emails
     assert_nothing_raised do
       assert_emails 1 do
-        TestHelperMailer.test.deliver
+        TestHelperMailer.test.deliver_now
       end
     end
   end
@@ -56,27 +56,27 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_repeated_assert_emails_calls
     assert_nothing_raised do
       assert_emails 1 do
-        TestHelperMailer.test.deliver
+        TestHelperMailer.test.deliver_now
       end
     end
 
     assert_nothing_raised do
       assert_emails 2 do
-        TestHelperMailer.test.deliver
-        TestHelperMailer.test.deliver
+        TestHelperMailer.test.deliver_now
+        TestHelperMailer.test.deliver_now
       end
     end
   end
 
   def test_assert_emails_with_no_block
     assert_nothing_raised do
-      TestHelperMailer.test.deliver
+      TestHelperMailer.test.deliver_now
       assert_emails 1
     end
 
     assert_nothing_raised do
-      TestHelperMailer.test.deliver
-      TestHelperMailer.test.deliver
+      TestHelperMailer.test.deliver_now
+      TestHelperMailer.test.deliver_now
       assert_emails 3
     end
   end
@@ -92,7 +92,7 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_emails_too_few_sent
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_emails 2 do
-        TestHelperMailer.test.deliver
+        TestHelperMailer.test.deliver_now
       end
     end
 
@@ -102,8 +102,8 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_emails_too_many_sent
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_emails 1 do
-        TestHelperMailer.test.deliver
-        TestHelperMailer.test.deliver
+        TestHelperMailer.test.deliver_now
+        TestHelperMailer.test.deliver_now
       end
     end
 
@@ -113,7 +113,7 @@ class TestHelperMailerTest < ActionMailer::TestCase
   def test_assert_no_emails_failure
     error = assert_raise ActiveSupport::TestCase::Assertion do
       assert_no_emails do
-        TestHelperMailer.test.deliver
+        TestHelperMailer.test.deliver_now
       end
     end
 
diff --git a/actionmailer/test/url_test.rb b/actionmailer/test/url_test.rb
index 589944fa69..e79b2ca978 100644
--- a/actionmailer/test/url_test.rb
+++ b/actionmailer/test/url_test.rb
@@ -68,7 +68,7 @@ class ActionMailerUrlTest < ActionMailer::TestCase
     created.message_id = '<123@456>'
     assert_equal expected.encoded, created.encoded
 
-    assert_nothing_raised { UrlTestMailer.signed_up_with_url(@recipient).deliver }
+    assert_nothing_raised { UrlTestMailer.signed_up_with_url(@recipient).deliver_now }
     assert_not_nil ActionMailer::Base.deliveries.first
     delivered = ActionMailer::Base.deliveries.first
 
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index aa056f5844..864026e9f2 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -311,6 +311,9 @@ Please refer to the [Changelog][action-mailer] for detailed changes.
 *   Deprecated `*_path` helpers in mailers. Always use `*_url` helpers instead.
     ([Pull Request](https://github.com/rails/rails/pull/15840))
 
+*   Deprecated `deliver` / `deliver!` in favour of `deliver_now` / `deliver_now!`.
+    ([Pull Request](https://github.com/rails/rails/pull/16582))
+
 ### Notable changes
 
 *   Introduced `deliver_later` which enqueues a job on the application's queue
diff --git a/guides/source/action_mailer_basics.md b/guides/source/action_mailer_basics.md
index 9ad9319255..6b6ce145e4 100644
--- a/guides/source/action_mailer_basics.md
+++ b/guides/source/action_mailer_basics.md
@@ -159,7 +159,10 @@ $ bin/rake db:migrate
 Now that we have a user model to play with, we will just edit the
 `app/controllers/users_controller.rb` make it instruct the `UserMailer` to deliver
 an email to the newly created user by editing the create action and inserting a
-call to `UserMailer.welcome_email` right after the user is successfully saved:
+call to `UserMailer.welcome_email` right after the user is successfully saved.
+
+Action Mailer is nicely integrated with Active Job so you can send emails outside
+of the request-response cycle, so the user doesn't have to wait on it:
 
 ```ruby
 class UsersController < ApplicationController
@@ -171,7 +174,7 @@ class UsersController < ApplicationController
     respond_to do |format|
       if @user.save
         # Tell the UserMailer to send a welcome email after save
-        UserMailer.welcome_email(@user).deliver
+        UserMailer.welcome_email(@user).deliver_later
 
         format.html { redirect_to(@user, notice: 'User was successfully created.') }
         format.json { render json: @user, status: :created, location: @user }
@@ -184,8 +187,29 @@ class UsersController < ApplicationController
 end
 ```
 
-The method `welcome_email` returns a `Mail::Message` object which can then just
-be told `deliver` to send itself out.
+NOTE: By default Active Job is configured to execute the job `:inline`. So you can
+use `deliver_later` now to send the emails and when you decide to start sending the
+email from a background job you'll just have to setup Active Job to use a queueing
+backend (Sidekiq, Resque, etc).
+
+If you want to send the emails right away (from a cronjob for example) just
+call `deliver_now`:
+
+```ruby
+class SendWeeklySummary
+  def run
+    User.find_each do |user|
+      UserMailer.weekly_summary(user).deliver_now
+    end
+  end
+end
+```
+
+The method `welcome_email` returns a `ActionMailer::MessageDelivery` object which
+can then just be told `deliver_now` or `deliver_later` to send itself out. The
+`ActionMailer::MessageDelivery` object is just a wrapper around a `Mail::Message`. If
+you want to inspect, alter or do anything else with the `Mail::Message` object you can
+access it with the `message` method on the `ActionMailer::MessageDelivery` object.
 
 ### Auto encoding header values
 
diff --git a/guides/source/active_job_basics.md b/guides/source/active_job_basics.md
index f7864f4961..5ce1dc43d1 100644
--- a/guides/source/active_job_basics.md
+++ b/guides/source/active_job_basics.md
@@ -200,10 +200,10 @@ of the request-response cycle, so the user doesn't have to wait on it. Active Jo
 is integrated with Action Mailer so you can easily send emails async:
 
 ```ruby
-# Instead of the classic
-UserMailer.welcome(@user).deliver
+# If you want to send the email now use #deliver_now
+UserMailer.welcome(@user).deliver_now
 
-# use #deliver later to send the email async
+# If you want to send the email through ActiveJob use #deliver_later
 UserMailer.welcome(@user).deliver_later
 ```
 
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index f9b46286c1..cb243c95f5 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -276,7 +276,7 @@ This may appear straightforward:
 ```ruby
 # This is very inefficient when the users table has thousands of rows.
 User.all.each do |user|
-  NewsMailer.weekly(user).deliver
+  NewsMailer.weekly(user).deliver_now
 end
 ```
 
@@ -292,7 +292,7 @@ The `find_each` method retrieves a batch of records and then yields _each_ recor
 
 ```ruby
 User.find_each do |user|
-  NewsMailer.weekly(user).deliver
+  NewsMailer.weekly(user).deliver_now
 end
 ```
 
@@ -300,7 +300,7 @@ To add conditions to a `find_each` operation you can chain other Active Record m
 
 ```ruby
 User.where(weekly_subscriber: true).find_each do |user|
-  NewsMailer.weekly(user).deliver
+  NewsMailer.weekly(user).deliver_now
 end
 ```
 
@@ -316,7 +316,7 @@ The `:batch_size` option allows you to specify the number of records to be retri
 
 ```ruby
 User.find_each(batch_size: 5000) do |user|
-  NewsMailer.weekly(user).deliver
+  NewsMailer.weekly(user).deliver_now
 end
 ```
 
@@ -328,7 +328,7 @@ For example, to send newsletters only to users with the primary key starting fro
 
 ```ruby
 User.find_each(start: 2000, batch_size: 5000) do |user|
-  NewsMailer.weekly(user).deliver
+  NewsMailer.weekly(user).deliver_now
 end
 ```
 
diff --git a/guides/source/testing.md b/guides/source/testing.md
index 2ecd560a87..d91f13699a 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -949,7 +949,7 @@ class UserMailerTest < ActionMailer::TestCase
   test "invite" do
     # Send the email, then test that it got queued
     email = UserMailer.create_invite('me@example.com',
-                                     'friend@example.com', Time.now).deliver
+                                     'friend@example.com', Time.now).deliver_now
     assert_not ActionMailer::Base.deliveries.empty?
 
     # Test the body of the sent email contains what we expect it to