I have a small office nework running SBS2003 with exchange server. For reasons beyond my control the client is not using exchange and their mx records do not direct incoming mail to their exchange server. Rather, they receiving and sending email via outlook 2003 by POP to a couple of different hosting accounts. Because of this I have the pop account set as the default account in outlook. However, the system for some reason keeps changing the default email account back to the exchange email account. As a result when email is sent they receive an undeliverable mail SMTP error 550 unable to relay email error message. As long as messages are sent via the POP3 email account everything is fine, but since outlook changes the default account back the problem keeps coming back. Any advice would be appreciated.