Hi, I'm running Exchange 2007 and Outlook 2003. When an user asks to a delivery notification, the user receive this: "Delivery to these recipients or distribution lists is complete, but delivery notification was not sent by the destination" If I sent an email internally the delivery notification is working but if I sent an email externally, we received this report. Thanks David

There is no requirement that a receiving host sensd or support DSNs. If you get this from *every* domain you send to it could be that your own outbound next hop or firewall doesn't support DNS, but if you don't get them from specific hosts or domains that's par for the course.