My network has 2 mailbox servers and one server for client access and hub trasport. No unified messaging configured. Last day we had a problem that none of the mails from user outlook is going through. All mails were pending in the outlook Outbox. The same thing were happened before I joined this company and there is a temporary work around in the paper. I stopped the exchange trasport service, then renamed the QUEUE2 folder in the Program Files\Microsoft\Exchange Server\TransportRoles\data by appending 'OLD' to it. Then restarted the trasport service, it creates a new QUEUE2 folder and after about 5 minutes all the users outlook outbox mails were successfully gone. What is the problem for this. Is there any permanent solution for this rather than this quick work around.

Anything in the event logs on the server? Is file level anti virus installed on the server?

Hi If mails are stopped in users outbox, then there is some problem in mail submission, exchange components like store driver and mailbox submission service are responsible for this. Did u notice any event related to disk or resource usage Problem definitely bcoz of resource i.e back preside or disk problem Inform if u find any events related to this...