1 files changed, 33 insertions, 5 deletions

diff --git a/app/mailers/emails/service_desk.rb b/app/mailers/emails/service_desk.rb
index 2953ec6cbe5..1295f978049 100644
--- a/app/mailers/emails/service_desk.rb
+++ b/app/mailers/emails/service_desk.rb
@@ -17,24 +17,30 @@ module Emails
       email_sender = sender(
         @support_bot.id,
         send_from_user_email: false,
-        sender_name: @project.service_desk_setting&.outgoing_name
+        sender_name: @service_desk_setting&.outgoing_name,
+        sender_email: service_desk_sender_email_address
       )
       options = service_desk_options(email_sender, 'thank_you', @issue.external_author)
                   .merge(subject: "Re: #{subject_base}")
 
-      mail_new_thread(@issue, options)
+      inject_service_desk_custom_email(mail_new_thread(@issue, options))
     end
 
     def service_desk_new_note_email(issue_id, note_id, recipient)
       @note = Note.find(note_id)
       setup_service_desk_mail(issue_id)
 
-      email_sender = sender(@note.author_id)
+      email_sender = sender(
+        @note.author_id,
+        send_from_user_email: false,
+        sender_email: service_desk_sender_email_address
+      )
+
       add_uploads_as_attachments if Feature.enabled?(:service_desk_new_note_email_native_attachments, @note.project)
       options = service_desk_options(email_sender, 'new_note', recipient)
                   .merge(subject: subject_base)
 
-      mail_answer_thread(@issue, options)
+      inject_service_desk_custom_email(mail_answer_thread(@issue, options))
     end
 
     private
@@ -44,6 +50,8 @@ module Emails
       @project = @issue.project
       @support_bot = User.support_bot
 
+      @service_desk_setting = @project.service_desk_setting
+
       @sent_notification = SentNotification.record(@issue, @support_bot.id, reply_key)
     end
 
@@ -55,10 +63,26 @@ module Emails
         next unless template_body = template_content(email_type)
 
         options[:body] = template_body
-        options[:content_type] = 'text/html'
+        options[:content_type] = 'text/html' unless attachments.present?
       end
     end
 
+    def inject_service_desk_custom_email(mail)
+      return mail unless service_desk_custom_email_enabled?
+
+      mail.delivery_method(::Mail::SMTP, @service_desk_setting.custom_email_delivery_options)
+    end
+
+    def service_desk_custom_email_enabled?
+      Feature.enabled?(:service_desk_custom_email, @project) && @service_desk_setting&.custom_email_enabled?
+    end
+
+    def service_desk_sender_email_address
+      return unless service_desk_custom_email_enabled?
+
+      @service_desk_setting.custom_email
+    end
+
     def template_content(email_type)
       template = Gitlab::Template::ServiceDeskTemplate.find(email_type, @project)
       text = substitute_template_replacements(template.content)
@@ -77,6 +101,10 @@ module Emails
         .gsub(/%\{\s*ISSUE_ID\s*\}/, issue_id)
         .gsub(/%\{\s*ISSUE_PATH\s*\}/, issue_path)
         .gsub(/%\{\s*NOTE_TEXT\s*\}/, note_text)
+        .gsub(/%\{\s*SYSTEM_HEADER\s*\}/, text_header_message.to_s)
+        .gsub(/%\{\s*SYSTEM_FOOTER\s*\}/, text_footer_message.to_s)
+        .gsub(/%\{\s*UNSUBSCRIBE_URL\s*\}/, unsubscribe_sent_notification_url(@sent_notification))
+        .gsub(/%\{\s*ADDITIONAL_TEXT\s*\}/, service_desk_email_additional_text.to_s)
     end
 
     def issue_id