I am running Exchange 5.5 SP4, Win NT 4.0 Server SP6a, Clients are Win98 using Outlook 97 or 2000. I am using the Exchange Server for internal e-mail only. We have a seperate External e-mail ISP. A seperate router is responsible for external e-mail and internet access for the clients. My question is that when client send bulk or group external e-mail it is going through the exchange server and getting returned undeliverable. However when they send only one at a time it works fine. Is there a way that I can bypass the exchanger server and go directly out to the external e-mail ISP or is there a correction I need to make on the Exchange Server to alow bulk or group mailings?