Convert models to use new search includes mechanism

app/models/dmail.rb

@@ -98,7 +98,7 @@ class Dmail < ApplicationRecord
     def search(params)
       q = super
 
-      q = q.search_attributes(params, :to, :from, :is_read, :is_deleted, :title, :body)
+      q = q.search_attributes(params, :is_read, :is_deleted, :title, :body)
       q = q.text_attribute_matches(:title, params[:title_matches])
       q = q.text_attribute_matches(:body, params[:message_matches], index_column: :message_index)
 
@@ -172,6 +172,10 @@ class Dmail < ApplicationRecord
     key ? "dmail ##{id}/#{self.key}" : "dmail ##{id}"
   end
 
+  def self.searchable_includes
+    [:to, :from]
+  end
+
   def self.available_includes
     [:owner, :to, :from]
   end