Our Internet provider’s servers recently went down. It has been back up for several days now. Before the service went down we had very little spam. Since it has come back up we are having excessive amounts of spam. One user has up to 500 a day. I contacted them and they said their firewall was back up and functioning, that something must have got into our Exchange Server. I have ran a scan on the server and found nothing. What could have got in to our server? I think it is on their end.