We were getting hammer by SPAM so I turned off the SMTP server to wait out the storm. When I restarted the SMTP Server I received about 10 bounced emails that were not in any of the outgoing queues. The dates on these emails spanned about a 3 month period and were to servers all round the world. I'm running Exchange 2003, on a Standard win 2k3 server. We have GFI MailEssentials & MailSecurity as SPAM / VA protection. There isn't a front-end server and I also remember this happen from time to time when the server reboots which I'm guessing also flush what ever queue these are hiding in. We are able to send emails to these domains e.g. I do not see then sitting in any of the out going queues.