Move existing email interceptors into the same module

config/initializers/additional_headers_interceptor.rb

-ActionMailer::Base.register_interceptor(AdditionalEmailHeadersInterceptor)
+ActionMailer::Base
+  .register_interceptor(::Gitlab::Email::Hook::AdditionalHeadersInterceptor)

config/initializers/disable_email_interceptor.rb

-# Interceptor in lib/disable_email_interceptor.rb
 unless Gitlab.config.gitlab.email_enabled
-  ActionMailer::Base.register_interceptor(DisableEmailInterceptor)
+  ActionMailer::Base.register_interceptor(::Gitlab::Email::Hook::DisableEmailInterceptor)
   ActionMailer::Base.logger = nil
 end

config/initializers/email_template_interceptor.rb

-# Interceptor in lib/email_template_interceptor.rb
-ActionMailer::Base.register_interceptor(EmailTemplateInterceptor)
+ActionMailer::Base.register_interceptor(::Gitlab::Email::Hook::EmailTemplateInterceptor)

lib/additional_email_headers_interceptor.rb

-class AdditionalEmailHeadersInterceptor
-  def self.delivering_email(message)
-    message.header['Auto-Submitted'] ||= 'auto-generated'
-    message.header['X-Auto-Response-Suppress'] ||= 'All'
-  end
-end

lib/disable_email_interceptor.rb

-# Read about interceptors in http://guides.rubyonrails.org/action_mailer_basics.html#intercepting-emails
-class DisableEmailInterceptor
-  def self.delivering_email(message)
-    message.perform_deliveries = false
-    Rails.logger.info "Emails disabled! Interceptor prevented sending mail #{message.subject}"
-  end
-end

lib/email_template_interceptor.rb

-# Read about interceptors in http://guides.rubyonrails.org/action_mailer_basics.html#intercepting-emails
-class EmailTemplateInterceptor
-  def self.delivering_email(message)
-    # Remove HTML part if HTML emails are disabled.
-    unless Gitlab::CurrentSettings.html_emails_enabled
-      message.parts.delete_if do |part|
-        part.content_type.start_with?('text/html')
-      end
-    end
-  end
-end

lib/gitlab/email/hook/additional_headers_interceptor.rb

+module Gitlab
+  module Email
+    module Hook
+      class AdditionalHeadersInterceptor
+        def self.delivering_email(message)
+          message.header['Auto-Submitted'] ||= 'auto-generated'
+          message.header['X-Auto-Response-Suppress'] ||= 'All'
+        end
+      end
+    end
+  end
+end

lib/gitlab/email/hook/disable_email_interceptor.rb

+module Gitlab
+  module Email
+    module Hook
+      class DisableEmailInterceptor
+        def self.delivering_email(message)
+          message.perform_deliveries = false
+
+          Rails.logger.info "Emails disabled! Interceptor prevented sending mail #{message.subject}"
+        end
+      end
+    end
+  end
+end

lib/gitlab/email/hook/email_template_interceptor.rb

+module Gitlab
+  module Email
+    module Hook
+      class EmailTemplateInterceptor
+        ##
+        # Remove HTML part if HTML emails are disabled.
+        #
+        def self.delivering_email(message)
+          unless Gitlab::CurrentSettings.html_emails_enabled
+            message.parts.delete_if do |part|
+              part.content_type.start_with?('text/html')
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/additional_email_headers_interceptor_spec.rb → spec/lib/gitlab/email/hook/additional_headers_interceptor_spec.rb

 require 'spec_helper'
 
-describe AdditionalEmailHeadersInterceptor do
+describe Gitlab::Email::Hook::AdditionalHeadersInterceptor do
   let(:mail) do
     ActionMailer::Base.mail(to: 'test@mail.com', from: 'info@mail.com', body: 'hello')
   end

spec/lib/disable_email_interceptor_spec.rb → spec/lib/gitlab/email/hook/disable_email_interceptor_spec.rb

 require 'spec_helper'
 
-describe DisableEmailInterceptor do
+describe Gitlab::Email::Hook::DisableEmailInterceptor do
   before do
     Mail.register_interceptor(described_class)
   end