Adding IP Block List
An administrator can configure list of IP addresses that are known as sources of spam, malicious code/viruses or some untrustworthy sources.
To do this follow these steps:
1. Expand Server Configuration.
2. Select Hub Transport to display Hub Transport servers.
3. From the center panel, select the Hub Transport server to which you wish to add the IP address or range to be blocked.
4. Click the Anti-spam tab.
5. Select IP Block List.
6. From the Actions pane, click the Properties shortcut to display the properties pages (alternatively, right-click IP Block List to select Properties from the context-sensitive menu).
7. On the Blocked Addresses tab, click on the Add button.
8. You can also add a single IP address (for example, x.x.x.4) or a lists of IP addresses.
9. Also if you need you can set an expiration time for the entry. Connections from the IP address or range will be allowed after the expiration time. The dialog box displays the expiration time, if one is entered, and its current state—whether active or not.
10. Click OK twice to close the IP Block List properties.

Thats it, you are done…