set state to 'open' when receiving reply on a ticket that is not in state 'new'

core/mail/protocol.py

@@ -180,12 +180,18 @@ def receive_email(envelope, log=None):
 
     reply = None
     if new:
+        # auto reply if new issue
         references = collect_references(active_issue_thread)
 
         reply_email = Email.objects.create(
             sender=recipient, recipient=sender, body="Thank you for your message.", subject="Message received",
             in_reply_to=header_message_id, event=target_event, issue_thread=active_issue_thread)
         reply = make_reply(reply_email, references)
+    else:
+        #change state if not new
+        if active_issue_thread.state != 'pending_new':
+            active_issue_thread.state = 'pending_open'
+            active_issue_thread.save()
 
     return email, new, reply