Configure a default timeout for the smtp delivery method

The default is set to 5 and only applied for new applications or
applications that opt-in for this new default.

Closes #42089.

[André Luis Leal Cardoso Junior + Rafael Mendonça França]

actionmailer/CHANGELOG.md

@@ -1,4 +1,6 @@
+*   Configures a default of 5 for both `open_timeout` and `read_timeout` for SMTP Settings.
 
+    *André Luis Leal Cardoso Junior*
 
 
 Please check [6-1-stable](https://github.com/rails/rails/blob/6-1-stable/actionmailer/CHANGELOG.md) for previous changes.

actionmailer/lib/action_mailer/railtie.rb

@@ -45,6 +45,15 @@ module ActionMailer
           self.delivery_job = delivery_job.constantize
         end
 
+        if smtp_settings = options.delete(:smtp_settings)
+          self.smtp_settings = smtp_settings
+        end
+
+        if smtp_timeout = options.delete(:smtp_timeout)
+          self.smtp_settings[:open_timeout] ||= smtp_timeout
+          self.smtp_settings[:read_timeout] ||= smtp_timeout
+        end
+
         options.each { |k, v| send("#{k}=", v) }
       end
 

guides/source/configuring.md

@@ -784,6 +784,9 @@ There are a number of settings available on `config.action_mailer`:
     * `:open_timeout` - Number of seconds to wait while attempting to open a connection.
     * `:read_timeout` - Number of seconds to wait until timing-out a read(2) call.
 
+* `config.action_mailer.smtp_timeout` allows to configure both the `:open_timeout` and `:read_timeout`
+values for `:smtp` delivery method.
+
 * `config.action_mailer.sendmail_settings` allows detailed configuration for the `sendmail` delivery method. It accepts a hash of options, which can include any of these options:
     * `:location` - The location of the sendmail executable. Defaults to `/usr/sbin/sendmail`.
     * `:arguments` - The command line arguments. Defaults to `-i`.
@@ -1063,6 +1066,7 @@ text/javascript image/svg+xml application/postscript application/x-shockwave-fla
 - `config.active_support.hash_digest_class`: `OpenSSL::Digest::SHA256`
 - `config.active_support.cache_format_version`: `7.0`
 - `config.action_dispatch.return_only_request_media_type_on_content_type`: `false`
+- `config.action_mailer.smtp_timeout`: `5`
 
 #### For '6.1', defaults from previous versions below and:
 
@@ -1141,6 +1145,7 @@ text/javascript image/svg+xml application/postscript application/x-shockwave-fla
 - `config.active_support.cache_format_version`: `6.1`
 - `config.action_dispatch.return_only_request_media_type_on_content_type`: `true`
 - `ActiveSupport.utc_to_local_returns_utc_offset_times`: `false`
+- `config.action_mailer.smtp_timeout`: `nil`
 
 ### Configuring a Database
 

railties/lib/rails/application/configuration.rb

@@ -212,6 +212,10 @@ module Rails
             active_support.remove_deprecated_time_with_zone_name = true
             active_support.cache_format_version = 7.0
           end
+
+          if respond_to?(:action_mailer)
+            action_mailer.smtp_timeout = 5
+          end
         else
           raise "Unknown version #{target_version.to_s.inspect}"
         end

railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_7_0.rb.tt

@@ -34,3 +34,6 @@
 # Only change this value after your application is fully deployed to Rails 7.0
 # and you have no plans to rollback.
 # config.active_support.cache_format_version = 7.0
+
+# Set both the `:open_timeout` and `:read_timeout` values for `:smtp` delivery method.
+# Rails.application.config.action_mailer.smtp_timeout = 5

railties/test/application/configuration_test.rb

@@ -2666,6 +2666,25 @@ module ApplicationTests
       assert_equal 308, Rails.application.config.action_dispatch.ssl_default_redirect_status
     end
 
+    test "Rails.application.config.action_mailer.smtp_settings have open_timeout and read_timeout defined as 5 in 7.0 defaults" do
+      remove_from_config '.*config\.load_defaults.*\n'
+      add_to_config 'config.load_defaults "7.0"'
+
+      app "development"
+
+      assert_equal 5, ActionMailer::Base.smtp_settings[:open_timeout]
+      assert_equal 5, ActionMailer::Base.smtp_settings[:read_timeout]
+    end
+
+    test "Rails.application.config.action_mailer.smtp_settings does not have open_timeout and read_timeout configured on other versions" do
+      remove_from_config '.*config\.load_defaults.*\n'
+
+      app "development"
+
+      assert_nil ActionMailer::Base.smtp_settings[:open_timeout]
+      assert_nil ActionMailer::Base.smtp_settings[:read_timeout]
+    end
+
     test "ActiveSupport.utc_to_local_returns_utc_offset_times is true in 6.1 defaults" do
       remove_from_config '.*config\.load_defaults.*\n'
       add_to_config 'config.load_defaults "6.1"'