- Open the ESM (Exchange System Manager) exchange management tool
- In Global Settings, right click on Message Delivery, then select Properties.
- In Message Delivery Properties, click Recipient Filtering tab.
- Put check on "Filter recipients who are not in the Directory">
Well you're not done yet, that's one part only. If you are not using a third-party anti-spam tools, you need to check your SMTP protocol setting. Here's how to:
- In ESM, go to Administrative Groups, First Administrative Group
- Expand Servers, then SERVER name.
- Expand Protocols, SMTP, right click on "Default SMTP Virtual Server" then Properties.
- In Default SMTP Virtual Server Properties, click Advance.
- In Advanced, click Edit
- Put check in "Apply Recipient Filter.
You don't need to restart your Exchange Server, now go check your anti-spam logs if traffic improve for your emails.
For Exchange Server 2007, I suggest you read this article from interjuncture.com website. Post comments or suggestions.
For Email Outsourcing Solution using Google Apps, please visit http://www.moscom.com/apps/ website for more details.