diff --git a/lib/email/message_builder.rb b/lib/email/message_builder.rb
index 79fe8a46b..4be0c89a4 100644
--- a/lib/email/message_builder.rb
+++ b/lib/email/message_builder.rb
@@ -132,10 +132,11 @@ module Email
     def header_args
       result = {}
       if @opts[:add_unsubscribe_link]
-        result['List-Unsubscribe'] = "<#{template_args[:user_preferences_url]}>"
+        unsubscribe_url = @template_args[:unsubscribe_url].presence || @template_args[:user_preferences_url]
+        result['List-Unsubscribe'] = "<#{unsubscribe_url}>"
       end
 
-      result['X-Discourse-Post-Id'] = @opts[:post_id].to_s if @opts[:post_id]
+      result['X-Discourse-Post-Id']  = @opts[:post_id].to_s  if @opts[:post_id]
       result['X-Discourse-Topic-Id'] = @opts[:topic_id].to_s if @opts[:topic_id]
 
       if allow_reply_by_email?