We just switched our email system from POP3 over to exchange server 2003. Our clients run Outlook 2003. We have an issuewith employees sending emails using their distribution lists. We get this exact error message: "An Internal support function returned an error". The only feasible answer I found was that there were duplicates in their contacts list that contain the same addresses in the Global Address List. The work-around was to change to display name in the ditribution list if the addresses happen to be included in the GLA. Any other suggestions?