Added ActionMailbox and ActiveMailer

app/mailboxes/application_mailbox.rb

@@ -0,0 +1,3 @@
+class ApplicationMailbox < ActionMailbox::Base
+  # routing /something/i => :somewhere
+end

app/mailers/user_mailer.rb

@@ -0,0 +1,2 @@
+class UserMailer < ApplicationMailer
+end

config/environments/production.rb

@@ -1,6 +1,9 @@
 require "active_support/core_ext/integer/time"
 
 Rails.application.configure do
+  # Prepare the ingress controller used to receive mail
+  # config.action_mailbox.ingress = :relay
+
   # Settings specified here will take precedence over those in config/application.rb.
 
   # Code is not reloaded between requests.

db/migrate/20240319142616_create_active_storage_tables.active_storage.rb

@@ -0,0 +1,57 @@
+# This migration comes from active_storage (originally 20170806125915)
+class CreateActiveStorageTables < ActiveRecord::Migration[7.0]
+  def change
+    # Use Active Record's configured type for primary and foreign keys
+    primary_key_type, foreign_key_type = primary_and_foreign_key_types
+
+    create_table :active_storage_blobs, id: primary_key_type do |t|
+      t.string   :key,          null: false
+      t.string   :filename,     null: false
+      t.string   :content_type
+      t.text     :metadata
+      t.string   :service_name, null: false
+      t.bigint   :byte_size,    null: false
+      t.string   :checksum
+
+      if connection.supports_datetime_with_precision?
+        t.datetime :created_at, precision: 6, null: false
+      else
+        t.datetime :created_at, null: false
+      end
+
+      t.index [ :key ], unique: true
+    end
+
+    create_table :active_storage_attachments, id: primary_key_type do |t|
+      t.string     :name,     null: false
+      t.references :record,   null: false, polymorphic: true, index: false, type: foreign_key_type
+      t.references :blob,     null: false, type: foreign_key_type
+
+      if connection.supports_datetime_with_precision?
+        t.datetime :created_at, precision: 6, null: false
+      else
+        t.datetime :created_at, null: false
+      end
+
+      t.index [ :record_type, :record_id, :name, :blob_id ], name: :index_active_storage_attachments_uniqueness, unique: true
+      t.foreign_key :active_storage_blobs, column: :blob_id
+    end
+
+    create_table :active_storage_variant_records, id: primary_key_type do |t|
+      t.belongs_to :blob, null: false, index: false, type: foreign_key_type
+      t.string :variation_digest, null: false
+
+      t.index [ :blob_id, :variation_digest ], name: :index_active_storage_variant_records_uniqueness, unique: true
+      t.foreign_key :active_storage_blobs, column: :blob_id
+    end
+  end
+
+  private
+    def primary_and_foreign_key_types
+      config = Rails.configuration.generators
+      setting = config.options[config.orm][:primary_key_type]
+      primary_key_type = setting || :primary_key
+      foreign_key_type = setting || :bigint
+      [primary_key_type, foreign_key_type]
+    end
+end

db/migrate/20240319142617_create_action_mailbox_tables.action_mailbox.rb

@@ -0,0 +1,20 @@
+# This migration comes from action_mailbox (originally 20180917164000)
+class CreateActionMailboxTables < ActiveRecord::Migration[6.0]
+  def change
+    create_table :action_mailbox_inbound_emails, id: primary_key_type do |t|
+      t.integer :status, default: 0, null: false
+      t.string  :message_id, null: false
+      t.string  :message_checksum, null: false
+
+      t.timestamps
+
+      t.index [ :message_id, :message_checksum ], name: "index_action_mailbox_inbound_emails_uniqueness", unique: true
+    end
+  end
+
+  private
+    def primary_key_type
+      config = Rails.configuration.generators
+      config.options[config.orm][:primary_key_type] || :primary_key
+    end
+end

test/mailers/previews/user_mailer_preview.rb

@@ -0,0 +1,4 @@
+# Preview all emails at http://localhost:3000/rails/mailers/user_mailer
+class UserMailerPreview < ActionMailer::Preview
+
+end

test/mailers/user_mailer_test.rb

@@ -0,0 +1,7 @@
+require "test_helper"
+
+class UserMailerTest < ActionMailer::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end