We have an SBS 2000 server running Exchange 2000. Nobody is receiving mail, internal or external. If you send a mail internally the mail goes to the outbox and then the sent items but never gets to the intended recipient. Exchange looks as if it is working fine and there are no obvious entries in the event log. The server has been rebooted and the problem persists. We do have Sophos Anti Virus mailmonitor running on the server, could this be at fault? I tried turning off the Sophos Mail Monitor service but to no avail. There are no messages in any of the smtp queues as seen in Exchange System Manager. Any ideas on how to find where these messages are and / or what is causing the problem? TIA Andy