This one is stumping me. Our setup: Exchange 2Ksp3 with front end / back end. 1 backend. 2 SMTP servers for sending/receiving mail to and from Exchange. and to scan for spam / viruses. If I send mail to a "garbage" mail adx, i.e. an address that doesn't exist within our domain, we do get an NDR. But it takes a long time (30 + minutes) and the message states (in part) A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients. Contact your administrator. I understand the logic, my exchange sees no adx for garbage@xxxxxxx and sends it to the smart host. The smart host gets it, sees it's for our domain, and sends it right back in. Now it's in a loop, hence the error. Our exchange server should be the able to decide that garbage@xxxxxxx doesn't exist and send a NDR immediately, it should not send out any mail for our domain to the smart host. Any ideas? Doug Stelley Asst. Network Admin. Olean General Hospital (716)375-7320 Never violate the Prime Directory! C:\ Confidential: The information contained in this message may be legally privileged and confidential information intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any release, dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error please notify the author immediately by replying to this message and deleting the original message. Thank you.