Answer

IIS 7.0 instructions:

You must first create the Virtual Directory where the synchronization data will be stored. Go to the IIS Manager, right click the Default Web Site, and select Add Virtual Directory

Enter MESyncAgent for the Alias and define a physical path for the files. You will need to create a new folder, but this can be done anywhere you wish.Keep note of the configured path for reference.
Select the MESynchAgent virtual directory and from the Features View, and double click SSL Settings
Disable the Require SSL checkbox and click Apply
Return to the Features View of the newly added virtual directory and double click Authentication
Ensure that only Basic Authentication is enabled, while the other options are disabled
Right click Basic Authentication and click Edit… to specify the Default Domain and Realm of the username and password used for authentication by the slave machines. Click OK and Apply.
Return to the Features View of the MESynchAgent virtual directory and double click BITS Uploads
Select Allow clients to upload files and select Use default settings from parent. Click Apply.

From the Internet Information Services (IIS) Manager console, right click the default website and select New > Virtual Directory
In the Virtual Directory Creation Wizard, key in MESynchAgent as an alias for the virtual directory and click Next
Specify a path where to store the contents for this virtual directory and click Next. Keep note of the configured path for reference.
Select the Read and Write checkboxes and uncheck all other checkboxes. Click Next and click Finish.
Right click the MESynchAgent virtual directory and select Properties
Select the Directory Security tab and in the Authentication and access control group click Edit
In Authenticated access group check Basic Authentication and specify the Default domain and Realm of the username and password used for authentication by the slave machines
Ensure that all other checkboxes are unchecked. Click OK.
Select the BITS Server Extension tab and select Allow clients to transfer data to this virtual directory
Click OK to close the virtual directory dialog properties

In the Configuration for the Anti Spam Synchronization, enter in the server names you will be synchronizing ,including the Master server
- Note: Slave servers automatically upload an archive file containing spam settings to the IIS virtual directory on the master server, so no virtual directory should be created on slave servers
In the URL field on the Slave server, specify the full URL to the virtual directory hosted on the master server in the following format: http://<master server domain name>/MESyncAgent
Check the Credentials required check box and key in the username/password used to authenticate with the master server
Choose either a manual or automatic uploading process
Make sure that the GFI MailEssentials Enterprise Transfer service is started on all servers that are being synchronized