How do I enable outbound HTTP requests via ISA?

Start the ISA Admin tool (Start - Programs - Microsoft ISA Server - ISA Administration Tool)

Expand the Arrays, the specific array, Access Policy

Select IP Packet Filters

Right click New and select Filter

Enter a filter name, e.g. HTTP and click Next

Select if this filter will apply to just the local server or all in the array. Click Next

The filter options are displayed
- Allow packet transmission
- Block packet transmission
Select Allow and click Next

Select the Custom filter type and click Next

Now you must select the Filter details:
- IP Protocol : TCP
- Direction: Both
- Local Port: Dynamic (1025-5000)
- Remote Port: Fixed port, Port number 80
Click here to view image
Click Next

Under the applicable section select 'Default external IP address' and click Next

Select 'All remote hosts' for the remote computers and click Next

Check the settings and click Finish