I am not 100% certain that this question does not belong in the DNS or exchange area but here goes. We have a Windows 2000 SBS running exchange to handle internal mail. External mail is handle through an SMTP account. Two users recently installed Office 2003. The mail accounts are set up so that the SMTP account is the default. When the users try to send mail to internal recipients the messages are not delivered and an 571 error message is generated. If I resend the message and choose the exchange server account the message goes through fine. This seems to tell me that the problem has to do with the way outlook 2003 routes mail. This was never a problem with earlier versions of outlook.
Please do not suggest configuring all internal and external mail to go through the exchange server, we are not ready to do that yet. I need a solution that will bridge us until we get to that point. I suspect there is a DNS or MX record change that can be made but I do not know what it should be. I have attempted some unsuccessfully. Hopefully someone can give me an answer. Thanks.