OUTGOING MAIL

Problem:
Many outgoing emails (not internal),generated under Outlook at the company workstations, are returning an email with the following subject:
“Delivery Status Notification (Delay)”.
Obviously, somewhere I have a bad configuration, wich I can’t find. If I send the emails, working from the webmail (not from outlook), there is no problem. I don’t have ISA Server configured; our external email traffic is managed by our ISP. Oppening the Exchange System Manager, Adminstrative Groups, first administrative group, Servers, queues: there are 26 queues listed, with the sites of the ‘failed-sent’ email’s .
Exchange Server is Exchange 2003.