diff --git a/app/models/mailer.rb b/app/models/mailer.rb
index 10d2fe900..5eaea71ba 100644
--- a/app/models/mailer.rb
+++ b/app/models/mailer.rb
@@ -187,13 +187,23 @@ class Mailer < ActionMailer::Base
       added_to_url = url_for(:controller => 'documents', :action => 'show', :id => container.id)
       added_to = "#{l(:label_document)}: #{container.title}"
     end
+    if attachments.length == 1
+      title = ": #{attachments[0].filename}"
+    elsif attachments.length > 1
+      title = ": #{l(:label_attachment_count,
+                   :filename => attachments[0].filename,
+                   :count => attachments.length-1)}"
+    else
+      # length == 0: never happens
+      title = ""
+    end
     redmine_headers 'Project' => container.project.identifier
     @attachments = attachments
     @user = user
     @added_to = added_to
     @added_to_url = added_to_url
     mail :to => user,
-      :subject => "[#{container.project.name}] #{l(:label_attachment_new)}"
+      :subject => "[#{container.project.name}] #{l(:label_attachment_new)}#{title}"
   end
 
   # Notifies users about new attachments
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 657297619..59e0fd04e 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -1420,3 +1420,4 @@ en:
   text_user_destroy_confirmation: "Are you sure you want to delete this user and remove all references to them? This cannot be undone. Often, locking a user instead of deleting them is the better solution. To confirm, please enter their login (%{login}) below."
   text_project_destroy_enter_identifier: "To confirm, please enter the project's identifier (%{identifier}) below."
   field_name_or_email_or_login: Name, email or login
+  label_attachment_count: "%{filename} and %{count} files"
diff --git a/config/locales/ja.yml b/config/locales/ja.yml
index 1faae3deb..3c8adf28c 100644
--- a/config/locales/ja.yml
+++ b/config/locales/ja.yml
@@ -1446,3 +1446,4 @@ ja:
   setting_copy_attachments_on_issue_copy: チケットをコピーするとき添付ファイルもコピー
   field_thousands_delimiter: 3桁区切り表示
   label_involved_principals: 作成者 / 直前担当者
+  label_attachment_count: "%{filename}、他%{count}件"