Hello, I developed an application that uses .NET's mail components. A user can configure the application to specify an smtp address, a sender's e-mail address (i.e. noreply@domain.com). A client configured their install to use their exchange server with domain authentication. I have a function that sends out a test e-mail with basic information. When run, it sends out the e-mail without a problem. When the actual data is sent out to *outgoing* e-mail addresses, it bombs with a message such as "An unknown exception Class: -4000 Subclass: -2146233088". With *internal* e-mails, it works fine. I changed the smtp server to a different server (i.e. one I use for my own use), and it worked fine for both internal and outgoing addresses. So, I'm thinking there is some setting on the Exchange server that needs to be looked at. Perhaps there is a filter of some sort that doesn't like the "noreplye@domain.com" and the fact that domain authentication is being used for the smtp server. Any help or suggestions would be much appreciated. Thanks, Dan. Dan Sionov

On the Exchange server, you can create a send connector without authentication, but for security reason, I will limit this connector only from the server that use your .net application. Ron

So you think this is a problem with authentication?Dan Sionov

Exact, if you want to be sure, you can do a telnet on the exchange server and do some smtp comment to send an email to external, you will see the error message. Ron