Exchange: Forwarding mail though your ISP’s SMTP server

In terms of working-around the issue with SORBS, while we wait for them to re-classify the ISP’s IP ranges as static, you can start forwarding email directly to your ISP’s SMTP server to avoid the block. Obviously, you’ll need to know the address of your ISP SMTP server (e.g. “smtp.youisp.com”), and if they require authentication.

This can be accomplished in Exchange 2003 by following the below steps:

1. Open Exchange System Manager (ESM).
2. Next click Servers>Connectors>"right-click" SMTP Connector", click Properties>General Tab
3. Select the button indicating "Forward all mail though this connector to the following smart hosts".
4. Type the name of your ISP's mail server

Next, verify that mail is going out correctly - check the queues to make sure nothing is getting hung up.

If you want to prove to youself that delivery is changing you can send a test message to an external mailbox that you have access to - both before and after you make the above changes. Then check the message headers - look at the “Received:” field - it should have changed from your PTR record, to your ISP’s SMTP server address.