Handle net-smtp mail dependency error for Ruby 3.1

actionmailbox/app/models/action_mailbox/inbound_email.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "mail"
+require "action_mailbox/mail_with_error_handling"
 
 module ActionMailbox
   # The +InboundEmail+ is an Active Record that keeps a reference to the raw email stored in Active Storage

actionmailbox/lib/action_mailbox/mail_ext.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "mail"
+require "action_mailbox/mail_with_error_handling"
 
 # The hope is to upstream most of these basic additions to the Mail gem's Mail object. But until then, here they lay!
 Dir["#{File.expand_path(File.dirname(__FILE__))}/mail_ext/*"].each { |path| require "action_mailbox/mail_ext/#{File.basename(path)}" }

actionmailbox/lib/action_mailbox/mail_with_error_handling.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+begin
+  require "mail"
+rescue LoadError => error
+  if error.message.match?(/net-stmp/)
+    $stderr.puts "You don't have net-stmp installed in your application. Please add it to your Gemfile and run bundle install"
+    raise
+  end
+end

actionmailer/lib/action_mailer.rb

@@ -57,7 +57,7 @@ module ActionMailer
   def self.eager_load!
     super
 
-    require "mail"
+    require "action_mailer/mail_with_error_handling"
     Mail.eager_autoload!
   end
 end

actionmailer/lib/action_mailer/base.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "mail"
+require "action_mailer/mail_with_error_handling"
 require "action_mailer/collector"
 require "active_support/core_ext/string/inflections"
 require "active_support/core_ext/hash/except"

actionmailer/lib/action_mailer/mail_with_error_handling.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+begin
+  require "mail"
+rescue LoadError => error
+  if error.message.match?(/net-stmp/)
+    $stderr.puts "You don't have net-stmp installed in your application. Please add it to your Gemfile and run bundle install"
+    raise
+  end
+end