add email events

app/mailers/application_mailer.rb

@@ -6,11 +6,32 @@ class ApplicationMailer < ActionMailer::Base
 
   register_interceptor ActionMailerConfigsInterceptor
 
+  register_observer ActionMailerEventsObserver
+
   before_action do
     ActiveStorage::Current.url_options = Docuseal.default_url_options
   end
 
+  after_action :set_message_metadata
+  after_action :set_message_uuid
+
   def default_url_options
     Docuseal.default_url_options
   end
+
+  def set_message_metadata
+    message.instance_variable_set(:@message_metadata, @message_metadata)
+  end
+
+  def set_message_uuid
+    message['X-Message-Uuid'] = SecureRandom.uuid
+  end
+
+  def assign_message_metadata(tag, record)
+    @message_metadata = {
+      'tag' => tag,
+      'record_id' => record.id,
+      'record_type' => record.class.name
+    }
+  end
 end

app/mailers/submitter_mailer.rb

@@ -26,6 +26,8 @@ class SubmitterMailer < ApplicationMailer
         DEFAULT_INVITATION_SUBJECT
       end
 
+    assign_message_metadata('submitter_invitation', @submitter)
+
     mail(
       to: @submitter.friendly_name,
       from: from_address_for_submitter(submitter),
@@ -58,6 +60,8 @@ class SubmitterMailer < ApplicationMailer
         %(#{submitter.submission.template.name} has been completed by #{submitters})
       end
 
+    assign_message_metadata('submitter_completed', @submitter)
+
     mail(from: from_address_for_submitter(submitter),
          to: to || (user.role == 'integration' ? user.friendly_name.sub(/\+\w+@/, '@') : user.friendly_name),
          subject:)
@@ -89,6 +93,8 @@ class SubmitterMailer < ApplicationMailer
         'Your document copy'
       end
 
+    assign_message_metadata('submitter_documents_copy', @submitter)
+
     mail(from: from_address_for_submitter(submitter),
          to: to || @submitter.friendly_name,
          reply_to: @submitter.preferences['reply_to'].presence ||

app/mailers/user_mailer.rb

@@ -6,6 +6,8 @@ class UserMailer < ApplicationMailer
     @user = user
     @token = @user.send(:set_reset_password_token)
 
+    assign_message_metadata('user_invitation', @user)
+
     mail(to: @user.friendly_name,
          subject: 'You are invited to DocuSeal')
   end