diff --git a/app/models/observer/ticket/article/communicate_email/background_job.rb b/app/models/observer/ticket/article/communicate_email/background_job.rb
index a579cde48..6634be4fb 100644
--- a/app/models/observer/ticket/article/communicate_email/background_job.rb
+++ b/app/models/observer/ticket/article/communicate_email/background_job.rb
@@ -7,8 +7,13 @@ class Observer::Ticket::Article::CommunicateEmail::BackgroundJob
     record = Ticket::Article.find(@article_id)
 
     # build subject
-    ticket  = Ticket.lookup(id: record.ticket_id)
-    subject = ticket.subject_build(record.subject)
+    ticket = Ticket.lookup(id: record.ticket_id)
+    article_count = Ticket::Article.where(ticket_id: ticket.id).count
+    subject = if article_count > 1
+                ticket.subject_build(record.subject, true)
+              else
+                ticket.subject_build(record.subject)
+              end
 
     # send email
     if !ticket.group.email_address_id
diff --git a/app/models/ticket/subject.rb b/app/models/ticket/subject.rb
index fb0044219..805d30bf3 100644
--- a/app/models/ticket/subject.rb
+++ b/app/models/ticket/subject.rb
@@ -6,7 +6,7 @@ module Ticket::Subject
 build new subject with ticket number in there
 
   ticket = Ticket.find(123)
-  result = ticket.subject_build('some subject')
+  result = ticket.subject_build('some subject', is_reply_true_false)
 
 returns
 
@@ -14,13 +14,17 @@ returns
 
 =end
 
-  def subject_build (subject)
+  def subject_build(subject, is_reply = false)
 
     # clena subject
     subject = subject_clean(subject)
 
     ticket_hook         = Setting.get('ticket_hook')
     ticket_hook_divider = Setting.get('ticket_hook_divider')
+    ticket_subject_re   = Setting.get('ticket_subject_re')
+    if is_reply && !ticket_subject_re.empty?
+      subject = "#{ticket_subject_re}: #{subject}"
+    end
 
     # none position
     if Setting.get('ticket_hook_position') == 'none'
@@ -49,7 +53,7 @@ returns
 
 =end
 
-  def subject_clean (subject)
+  def subject_clean(subject)
     ticket_hook         = Setting.get('ticket_hook')
     ticket_hook_divider = Setting.get('ticket_hook_divider')
     ticket_subject_size = Setting.get('ticket_subject_size')
diff --git a/test/unit/ticket_test.rb b/test/unit/ticket_test.rb
index 1c924c470..e87d66aa1 100644
--- a/test/unit/ticket_test.rb
+++ b/test/unit/ticket_test.rb
@@ -263,4 +263,23 @@ class TicketTest < ActiveSupport::TestCase
     lookup_ticket = Ticket.find_by('pending_time <= ?', Time.zone.now)
     assert_nil(lookup_ticket, 'ticket.pending_time processed verify')
   end
+
+  test 'ticket subject' do
+
+    ticket1 = Ticket.create(
+      title: 'subject test 1',
+      group: Group.lookup(name: 'Users'),
+      customer_id: 2,
+      state: Ticket::State.lookup(name: 'new'),
+      priority: Ticket::Priority.lookup(name: '2 normal'),
+      updated_by_id: 1,
+      created_by_id: 1,
+    )
+    assert_equal('subject test 1', ticket1.title)
+    assert_equal("ABC subject test 1 [Ticket##{ticket1.number}]", ticket1.subject_build('ABC subject test 1'))
+    assert_equal("RE: ABC subject test 1 [Ticket##{ticket1.number}]", ticket1.subject_build('ABC subject test 1', true))
+    ticket1.destroy
+
+  end
+
 end