diff --git a/lib/generators/rspec/mailbox/mailbox_generator.rb b/lib/generators/rspec/mailbox/mailbox_generator.rb
new file mode 100644
index 0000000000..1277326e3b
--- /dev/null
+++ b/lib/generators/rspec/mailbox/mailbox_generator.rb
@@ -0,0 +1,14 @@
+require 'generators/rspec'
+
+module Rspec
+  module Generators
+    # @private
+    class MailboxGenerator < Base
+      def create_mailbox_spec
+        template('mailbox_spec.rb.erb',
+                 File.join('spec/mailboxes', class_path, "#{file_name}_mailbox_spec.rb")
+        )
+      end
+    end
+  end
+end
diff --git a/lib/generators/rspec/mailbox/templates/mailbox_spec.rb.erb b/lib/generators/rspec/mailbox/templates/mailbox_spec.rb.erb
new file mode 100644
index 0000000000..3766bd3915
--- /dev/null
+++ b/lib/generators/rspec/mailbox/templates/mailbox_spec.rb.erb
@@ -0,0 +1,7 @@
+require 'rails_helper'
+
+<% module_namespacing do -%>
+RSpec.describe <%= class_name %>Mailbox, <%= type_metatag(:mailbox) %> do
+  pending "add some examples to (or delete) #{__FILE__}"
+end
+<% end -%>
diff --git a/lib/rspec/rails/configuration.rb b/lib/rspec/rails/configuration.rb
index 6869b88437..c61df85886 100644
--- a/lib/rspec/rails/configuration.rb
+++ b/lib/rspec/rails/configuration.rb
@@ -34,7 +34,8 @@ class Configuration
       :routing    => %w[spec routing],
       :view       => %w[spec views],
       :feature    => %w[spec features],
-      :system     => %w[spec system]
+      :system     => %w[spec system],
+      :mailbox    => %w[spec mailboxes]
     }
 
     # Sets up the different example group modules for the different spec types
@@ -140,6 +141,10 @@ def filter_rails_from_backtrace!
       if defined?(ActiveJob)
         config.include RSpec::Rails::JobExampleGroup, :type => :job
       end
+
+      if defined?(ActionMailbox)
+        config.include RSpec::Rails::MailboxExampleGroup, :type => :mailbox
+      end
     end
     # rubocop:enable Style/MethodLength
 
diff --git a/lib/rspec/rails/example.rb b/lib/rspec/rails/example.rb
index 4ad8507a95..56e4160848 100644
--- a/lib/rspec/rails/example.rb
+++ b/lib/rspec/rails/example.rb
@@ -9,3 +9,4 @@
 require 'rspec/rails/example/job_example_group'
 require 'rspec/rails/example/feature_example_group'
 require 'rspec/rails/example/system_example_group'
+require 'rspec/rails/example/mailbox_example_group'
diff --git a/lib/rspec/rails/example/mailbox_example_group.rb b/lib/rspec/rails/example/mailbox_example_group.rb
new file mode 100644
index 0000000000..97150b8f88
--- /dev/null
+++ b/lib/rspec/rails/example/mailbox_example_group.rb
@@ -0,0 +1,74 @@
+module RSpec
+  module Rails
+    # @api public
+    # Container module for mailbox spec functionality.
+    module MailboxExampleGroup
+      extend ActiveSupport::Concern
+
+      if RSpec::Rails::FeatureCheck.has_action_mailbox?
+        require 'action_mailbox/test_helper'
+        extend ::ActionMailbox::TestHelper
+
+        def self.create_inbound_email(arg)
+          case arg
+          when Hash
+            create_inbound_email_from_mail(arg)
+          else
+            create_inbound_email_from_source(arg.to_s)
+          end
+        end
+      else
+        def self.create_inbound_email(_arg)
+          raise "Could not load ActionMailer::TestHelper"
+        end
+      end
+
+      class_methods do
+        # @private
+        def mailbox_class
+          described_class
+        end
+      end
+
+      included do
+        subject { described_class }
+      end
+
+      # Verify the status of any inbound email
+      #
+      # @example
+      #     describe ForwardsMailbox do
+      #       it "can describe what happened to the inbound email" do
+      #         mail = process(args)
+      #
+      #         # can use any of:
+      #         expect(mail).to have_been_delivered
+      #         expect(mail).to have_bounced
+      #         expect(mail).to have_failed
+      #       end
+      #     end
+      def have_been_delivered
+        satisfy('have been delivered', &:delivered?)
+      end
+
+      def have_bounced
+        satisfy('have bounced', &:bounced?)
+      end
+
+      def have_failed
+        satisfy('have failed', &:failed?)
+      end
+
+      # Process an inbound email message directly, bypassing routing.
+      #
+      # @param message [Hash, Mail::Message] a mail message or hash of
+      #   attributes used to build one
+      # @return [ActionMaibox::InboundMessage]
+      def process(message)
+        MailboxExampleGroup.create_inbound_email(message).tap do |mail|
+          self.class.mailbox_class.receive(mail)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/rspec/rails/feature_check.rb b/lib/rspec/rails/feature_check.rb
index ed92131771..35006f2c8c 100644
--- a/lib/rspec/rails/feature_check.rb
+++ b/lib/rspec/rails/feature_check.rb
@@ -38,6 +38,10 @@ def has_action_mailer_show_preview?
           ::ActionMailer::Base.respond_to?(:show_previews=)
       end
 
+      def has_action_mailbox?
+        defined?(::ActionMailbox)
+      end
+
       def has_1_9_hash_syntax?
         ::Rails::VERSION::STRING > '4.0'
       end
diff --git a/lib/rspec/rails/matchers.rb b/lib/rspec/rails/matchers.rb
index dd37321e80..c90412519e 100644
--- a/lib/rspec/rails/matchers.rb
+++ b/lib/rspec/rails/matchers.rb
@@ -20,6 +20,11 @@ module Matchers
 require 'rspec/rails/matchers/relation_match_array'
 require 'rspec/rails/matchers/be_valid'
 require 'rspec/rails/matchers/have_http_status'
+
 if RSpec::Rails::FeatureCheck.has_active_job?
   require 'rspec/rails/matchers/active_job'
 end
+
+if RSpec::Rails::FeatureCheck.has_action_mailbox?
+  require 'rspec/rails/matchers/action_mailbox'
+end
diff --git a/lib/rspec/rails/matchers/action_mailbox.rb b/lib/rspec/rails/matchers/action_mailbox.rb
new file mode 100644
index 0000000000..c5392cb225
--- /dev/null
+++ b/lib/rspec/rails/matchers/action_mailbox.rb
@@ -0,0 +1,64 @@
+module RSpec
+  module Rails
+    module Matchers
+      # Namespace for various implementations of ActionMailbox features
+      #
+      # @api private
+      module ActionMailbox
+        # @private
+        class Base < RSpec::Rails::Matchers::BaseMatcher
+          private
+
+          def create_inbound_email(message)
+            RSpec::Rails::MailboxExampleGroup.create_inbound_email(message)
+          end
+        end
+
+        # @private
+        class ReceiveInboundEmail < Base
+          def initialize(message)
+            super()
+
+            @inbound_email = create_inbound_email(message)
+          end
+
+          def matches?(mailbox)
+            @mailbox  = mailbox
+            @receiver = ApplicationMailbox.router.send(:match_to_mailbox, inbound_email)
+
+            @receiver == @mailbox
+          end
+
+          def failure_message
+            "expected #{describe_inbound_email} to route to #{mailbox}".tap do |msg|
+              if receiver
+                msg << ", but routed to #{receiver} instead"
+              end
+            end
+          end
+
+          def failure_message_when_negated
+            "expected #{describe_inbound_email} not to route to #{mailbox}"
+          end
+
+        private
+
+          attr_reader :inbound_email, :mailbox, :receiver
+
+          def describe_inbound_email
+            "mail to #{inbound_email.mail.to.to_sentence}"
+          end
+        end
+      end
+
+      # @api public
+      # Passes if the given inbound email would be routed to the subject inbox.
+      #
+      # @param message [Hash, Mail::Message] a mail message or hash of
+      #   attributes used to build one
+      def receive_inbound_email(message)
+        ActionMailbox::ReceiveInboundEmail.new(message)
+      end
+    end
+  end
+end
diff --git a/spec/generators/rspec/mailbox/mailbox_generator_spec.rb b/spec/generators/rspec/mailbox/mailbox_generator_spec.rb
new file mode 100644
index 0000000000..3a80a3c3ac
--- /dev/null
+++ b/spec/generators/rspec/mailbox/mailbox_generator_spec.rb
@@ -0,0 +1,18 @@
+# Generators are not automatically loaded by Rails
+require 'generators/rspec/mailbox/mailbox_generator'
+require 'support/generators'
+
+RSpec.describe Rspec::Generators::MailboxGenerator, :type => :generator, :skip => !RSpec::Rails::FeatureCheck.has_action_mailbox? do
+  setup_default_destination
+
+  describe 'the generated files' do
+    before { run_generator %w[forwards] }
+
+    subject { file('spec/mailboxes/forwards_mailbox_spec.rb') }
+
+    it { is_expected.to exist }
+    it { is_expected.to contain(/require 'rails_helper'/) }
+    it { is_expected.to contain(/describe ForwardsMailbox, #{type_metatag(:mailbox)}/) }
+
+  end
+end
diff --git a/spec/rspec/rails/example/mailbox_example_group_spec.rb b/spec/rspec/rails/example/mailbox_example_group_spec.rb
new file mode 100644
index 0000000000..42a9adaf17
--- /dev/null
+++ b/spec/rspec/rails/example/mailbox_example_group_spec.rb
@@ -0,0 +1,83 @@
+require "spec_helper"
+require "rspec/rails/feature_check"
+
+class ApplicationMailbox
+  class << self
+    attr_accessor :received
+
+    def receive(*)
+      self.received += 1
+    end
+  end
+
+  self.received = 0
+end
+
+module RSpec
+  module Rails
+    describe MailboxExampleGroup, :skip => !RSpec::Rails::FeatureCheck.has_active_job? do
+      it_behaves_like "an rspec-rails example group mixin", :mailbox,
+                      './spec/mailboxes/', '.\\spec\\mailboxes\\'
+
+      def group_for(klass)
+        RSpec::Core::ExampleGroup.describe klass do
+          include MailboxExampleGroup
+        end
+      end
+
+      let(:group) { group_for(::ApplicationMailbox) }
+      let(:example) { group.new }
+
+      describe '#have_been_delivered' do
+        it 'raises on undelivered mail' do
+          expect {
+            expect(double('IncomingEmail', :delivered? => false)).to example.have_been_delivered
+          }.to raise_error(/have been delivered/)
+        end
+
+        it 'does not raise otherwise' do
+          expect(double('IncomingEmail', :delivered? => true)).to example.have_been_delivered
+        end
+      end
+
+      describe '#have_bounced' do
+        it 'raises on unbounced mail' do
+          expect {
+            expect(double('IncomingEmail', :bounced? => false)).to example.have_bounced
+          }.to raise_error(/have bounced/)
+        end
+
+        it 'does not raise otherwise' do
+          expect(double('IncomingEmail', :bounced? => true)).to example.have_bounced
+        end
+      end
+
+      describe '#have_failed' do
+        it 'raises on unfailed mail' do
+          expect {
+            expect(double('IncomingEmail', :failed? => false)).to example.have_failed
+          }.to raise_error(/have failed/)
+        end
+
+        it 'does not raise otherwise' do
+          expect(double('IncomingEmail', :failed? => true)).to example.have_failed
+        end
+      end
+
+      describe '#process' do
+        before do
+          allow(RSpec::Rails::MailboxExampleGroup).to receive(:create_inbound_email) do |attributes|
+            mail = double('Mail::Message', attributes)
+            double('InboundEmail', :mail => mail)
+          end
+        end
+
+        it 'sends mail to the mailbox' do
+          expect {
+            example.process(:to => ['test@example.com'])
+          }.to change(::ApplicationMailbox, :received).by(1)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/rspec/rails/matchers/action_mailbox_spec.rb b/spec/rspec/rails/matchers/action_mailbox_spec.rb
new file mode 100644
index 0000000000..99577d13d2
--- /dev/null
+++ b/spec/rspec/rails/matchers/action_mailbox_spec.rb
@@ -0,0 +1,52 @@
+require "spec_helper"
+require "rspec/rails/feature_check"
+
+class ApplicationMailbox
+  class Router
+    def match_to_mailbox(*)
+      Inbox
+    end
+  end
+
+  def self.router
+    Router.new
+  end
+end
+
+class Inbox < ApplicationMailbox; end
+class Otherbox < ApplicationMailbox; end
+
+RSpec.describe "ActionMailbox matchers", :skip => !RSpec::Rails::FeatureCheck.has_active_job? do
+  include RSpec::Rails::Matchers::ActionMailbox
+
+  describe "receive_inbound_email" do
+    let(:to) { ['to@example.com'] }
+
+    before do
+      allow(RSpec::Rails::MailboxExampleGroup).to receive(:create_inbound_email) do |attributes|
+        mail = double('Mail::Message', attributes)
+        double('InboundEmail', :mail => mail)
+      end
+    end
+
+    it "passes when it receives inbound email" do
+      expect(Inbox).to receive_inbound_email(:to => to)
+    end
+
+    it "passes when negated when it doesn't receive inbound email" do
+      expect(Otherbox).not_to receive_inbound_email(:to => to)
+    end
+
+    it "fails when it doesn't receive inbound email" do
+      expect {
+        expect(Otherbox).to receive_inbound_email(:to => to)
+      }.to raise_error(/expected mail to to@example.com to route to Otherbox, but routed to Inbox/)
+    end
+
+    it "fails when negated when it receives inbound email" do
+      expect {
+        expect(Inbox).not_to receive_inbound_email(:to => to)
+      }.to raise_error(/expected mail to to@example.com not to route to Inbox/)
+    end
+  end
+end